LEMON SHARK

ORDER Carcharhiniformes

FAMILY Carcharhinidae

GROUP 4: FISH

GENUS Ex SPECIES Negaprion brevirostris

The lemon shark is named for its light yellowish brown color. This dangerous fish has a broad, rounded snout and two dorsal fins

situated far back along its body.

KEY FACTS SIZES Length: Up to 11 ft. in the wild.

8-81/2 ft. in captivity.

Weight: Up to 400 lb.

BREEDING

Sexual maturity: Not known . Mating: Late spring and early

summer.

Gestation: About 9 months.

No. of young: Up to 10 pups.

LIFESTYLE

Habit: Young fish gather in small

schools. Adult fish are solitary.

Diet: Mullet, ladyfish, small groupers in inshore waters.

Mackerel, bonito, and squid in offshore waters.

Lifespan: Not known.

RELATED SPECIES

The sicklefin lemon shark,

Negaprion acutidens, is common

in the Red Sea and in the Pacific

and Indian oceans.

Range of the lemon shark.

DISTRIBUTION In shallow waters around the east coasts of North and

South America, along the west coasts of Central and South

America, and down the west coast of Africa .

CONSERVATION

Appears to thrive both in the w ild and in captivity.

Increasing chemical pollution, especially in shallow water,

threatens its future .

THE LEMON SHARK AND ITS RELATIVES

• . 41 ~

One of the smallest members of the shark family is the pygmy shark, which rarely reaches more than eight inches in length.

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The lemon shark (above) measures 11 feet, the length of a small family car, and is a fearsome hunter.

The largest shark. the 65-foot-long, 70-ton whale shark (below), is a gentle giant. feeding only on plankton .

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The lemon shark has distinctive upright and

symmetrical teeth. The sharp pointed teeth in

its lower jaw catch and hold its prey firmly

while the serrated teeth in the upper jaw

cut away at the flesh.

~ HABITAT The lemon shark inhabits wa- tral and South America, and ters along the east coasts of down the west coast of North and South America Africa. It prefers shallow and from New Jersey to Brazil, medium-depth bay water to along the west coasts of Cen- the deep open sea.

~ LEMON SHARK & MAN A mature lemon shark in cap­tivity can be dangerous, sud­denly turning violent. In the wild, many large fish have been known to attack people in shallow water.

Their large size and prefer­ence for shallow water make them particularly dangerous; they easily come into contact

with human beings. Scientists have conducted

numerous experiments with the lemon shark. It is at­tracted by the bright colors of orange and yellow wet suits and life raft equipment. It also responds to low-frequency sound waves produced by in­jured fish or people.

DID YOU KNOW? • The lemon shark's habits are learned from those in captivity. Lemon sharks are easy to keep .

• United States scientists have tested anesthetics, cardiac re­sponses, adaptation to dark­ness, and eye movements on this species.

• Lemon sharks have been bred in captivity. Dr. Eugene Clarke hand-raised a litter of lemon sharks at the Cape Haze marine laboratory in Florida until a newly intro­duced male lemon shark ate the pups.

• Helicopter engine noise over shipwrecks is believed to attract sharks. The pulsating beat of the rotor blades sends out the right sound frequen­cies for sharks to hear.

• Like other sharks, lemon sharks are easily provoked by splashing in the water.

~ FOOD I'< HUNTING The lemon shark hunts and eats any good-sized fish. In­shore, it eats mullet, ladyfish, and small groupers. In deeper water, it feeds on mackerel, bonito, and squid. Juvenile lemon sharks, called pups, band together to hunt in shal­low water. Mature lemon sharks hunt alone, but they form large groups where huge shoals of fish occur.

Cannibalism (a species eat­ing another of its own kind) is very common among lemon sharks. This is why pups stay in safer shallow waters, out of reach of the larger fish, until they mature.

Left: An adult lemon shark hunts alone, using its highly developed senses of smell and hearing to detect prey.

Right: Young sharks band together in the warm shallow coastal waters to hunt small fish and avoid larger shark predators.

~ -B-RE-E-O-IN- C--------------------------------------------

There is more known about the lemon shark's breeding in captivity than in the wild. Like most male sharks, the domi­nant male lemon shark can bite and injure the female during mating.

The females give birth to up to 10 young in late spring and early summer in shallow wa­ter. Each newborn pup stays on the seabed for a short time before swimming away to break the umbilical cord.

From birth, the pups must fend for themselves. They form small schools with other young sharks to hunt inshore fish like mullet and mangrove jack.

Below: After giving birth a female trails the afterbirth behind her.

HAGFISH

ORDER Myxini

FAMILY Myxinidae

GROUP 4: FISH GENUS & SPECIES Myxine glutinosa

The North Atlantic hagfish lives on the seabed of the northern oceans. It emerges from the mud to feed

on both dead and living fish.

KEY FACTS

SIZES

Length: Usually about 1 ft . Occasionally up to 2 ft.

BREEDING

Mating season: Spring and

summer.

No. of eggs: About 30 oval eggs,

each 1 in. long.

LIFESTYLE

Habit: Solitary; lives in burrows on

the muddy ocean floor.

Diet: Dead fish, bottom-living

crustaceans, and worms.

Lifespan: Unknown.

RELATED SPECIES

There are 32 species of hagfish in

the order Myxiniformes. They are

often grouped with the lampreys

(40 species) in the class Agnatha (jawless fishes), but their true

relationship is uncertain.

Prey: Usually dead fish . Sometimes injured , diseased , or dying fish or fish caught in nets.

Range of the North Atlantic hagfish.

DISTRIBUTION

Found in European coastal waters from Norway to Corsica

and in North America from northern Canada to North

Carolina.

CONSERVATION

Although threatened by marine pollution, like all sea

creatures, the hagfish is not fished commercially and is in

no immediate danger.

Feeding: Bores into prey using sucking mouth and rasplike tongue. Sometimes twists its slimy, eel-like body into knots, which it presses against prey for leverage.

The muscular, jawless mouth and single nostril are surrounded by sensitive barbels (feelers) .

The slimy and boneless North Atlantic hagfish

is one of the most successful scavengers in

the cold-water oceans/ in spite of the

fact that the fish is almost totally blind/

has no jaw or teeth/ and does not

have a true heart.

~ CHARACTERISTICS

The slimy, eyeless, jawless, boneless, and wormlike hagfish has no known living relatives. But it does share many features with another group of eel-like fish called lampreys.

Lampreys and hagfish are considered to be less highly evolved than other fish. The hagfish's spine, for example, is a flexible rod of gristle, rather than the chain of vertebrae found in nearly all other fish . The hagfish has no bones at all, and this gristly spine provides the only reinforce­ment for its muscular body.

Below: A hagfish is coiled near the cold, sunless floor of the ocean.

The hagfish's jawless mouth is no more than a small, muscular slit surrounded by sensitive barbels (feelers). It gnaws its food with a raspy tongue. A layer of skin covers the hagfish's tiny eyes, making it unable to see anything but light and dark.

The hagfish's most unusual feature is slime, which oozes from glands in rows down its sides. The slime lubricates its skin as the hagfish gnaws its way into its prey. The hagfish produces so much slime that it must frequently scrape off the excess by knotting its body and sliding through the coils.

~ FOOD & FEEDING The North Atlantic hagfish is a predator as well as a scavenger: it feeds on both live and dead fish . It also eats small crustaceans and bottom-living worms. Sometimes the hagfish attacks fish that are trapped in nets and cannot escape.

The hagfish's limited sense of smell allows it to detect prey only at close range. Once it finds prey,

~BREEDI NG Little is known about the North Atlantic hagfish's breeding behavior. Each hagfish grows an internal ovary or testis (female or male reproduction organ), but it has no visible organs. This suggests that eggs are probably fertilized exter­nally by sperm that the male sheds as he swims over the egg cluster.

No more than 30 inch-long eggs are laid at a time. The eggs have tufts of sticky fibers

such as a dead fish, the hagfish begins to cut away at its skin with its raspy, toothed tongue. Within minutes it has bored into the fish's body and begins to suck its flesh out.

When the prey's skin is especially tough, the hagfish knots its eel-like body and pushes against the fish for leverage.

at each end that fasten them together and to the seabed. This protects them from being swept into open waters, where they would be eaten by other fish .

Unlike most fish, which hatch as larvae, the hagfish emerges from its egg fully formed. Within hours of hatching, each young fish begins to search for the scent of its first meal.

Right: Sticky fibers fasten the eggs to one another and to the seabed.

DID YOU KNOW? • Instead of a heart, the hag­fish has a series of pumps that push blood from one part of its body to the next. • A single North Atlantic hag­fish will turn the entire con­tents of a bucket of seawater into slime. • A hagfish's single nostril

'----

frequently becomes clogged with slime. The fish simply sneezes to clear it. • A hagfish's wound heals cleanly and quickly. Scientists believe that the protective coating of slime around the fish's body has antiseptic qualities that prevent infection.

Left: The hagfish can swim on either its abdomen or its back by making muscular side­to-side contractions with its long body. It extends its barbels, or feelers, to search the water for prey, but it probably cannot detect scent beyond two feet.

CARD 24 ] PARROTFISH

~------------------------ GROUP 4: FI SH

~ ORDER Perciformes

FAMILY Scaridae

GENUS Scams

The parrotfish grazes the coral reefs of tropical oceans, cropping seaweed with its tough, beaklike teeth. It even

bites through coral to get at the food within.

KEY FACTS

SIZES

Length: Varies from 8 in.-3 ft. Some reach 6 ft. or longer.

~ BREEDING Mating season: Early summer. Eggs: Spherical or oval. Released in large numbers into open

water. Hatching time: Within 24 hours.

LIFESTYLE

Habit: Feeds in coral reefs. Diet: Reef-living algae (seaweed and plankton), and coral polyps.

lifespan: 5 years.

RELATED SPECIES

The parrotfish belongs to the order of perchlike fish, which

includes some 8,000 species. Its closest relatives are the wrasses,

which are also reef fish.

Range of the parrotfish.

DISTRIBUTION

Parrotfish live in the tropical Atlantic and Indo-Pacific oceans, wherever there are coral reefs to provide suitable feeding and breeding sites.

CONSERVATION

The survival of the parrotfish depends upon the future of their coral reef habitats. Although not endangered, they live

in areas increasingly disturbed by man.

PARROTFISH AND THEIR SPAWNING GROUNDS

The females' eggs are fertilized by a few males, often in huge numbers, at the spawning ground near a reef. Tidal currents wash the eggs away from predators in the reef and out to sea, where they hatch. Tides sweep the newly hatched parrotfish larvae back to the lagoon to mature­usually into females.

Immature female (1) grows and becomes a breeding female (2) that produces eggs.

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Tidal currents

Spawning ground

Breeding female changes into a primary male (3)

that grows and becomes

a breeding male (4) that

fertilizes eggs.

0160200231 PACKET 23

Parrotfish are sociable by day,

swimming in large schools as they

forage for food in the coral reef. But by

night each fish retires to a private refuge

and seals itself into a cocoon of mucus

that keeps it safe from predators.

~ HABITS As the tide rises over the coral reef, schools of parrotfish graze on the algae that grows upon the coral. The big males are much more vibrant in col­or than the smaller, drab fe­males. Normally they propel themselves through the water by rowing forward slowly with their small pectoral fins, but if a predator appears-a shark or grouper, for in­stance-they flick their tails and scatter in all directions.

Some parrotfish spend the night in an unusual way. After a day of feeding, each fish retreats to a favorite coral cave or crevice and secretes a

film of mucus from glands in its skin. Within half an hour the film builds into a giant bubble of mucus that encap­sulates the sleeping fish . The bubble has openings in the front and rear that allow wa­ter through for respiration. The clear mucus is only visible because of scraps of weed and sand that stick to it.

The mucus bubble proba­bly acts as a barrier to scent. Moray eels and other night predators track their prey by smell, so a fish that spends the night in a scent-proof capsule has a good chance of survival.

~ BREEDING Parrotfish undergo a remark­able sex change during their lifecycle. Most parrotfish are functioning females when they become sexually mature. During their first reproductive season they lay eggs. As they grow older, however, they change into males.

The transition is marked by a color change. One species, for example, is drab olive green in the female phase and bright electric blue and emerald green when it becomes a male. Older males in many

Left: Parrotfish are immune to the stinging cells of coral polyps.

species also develop bulging foreheads.

Many fish die young, so males are often scarce. When the fish spawn, a few males fertilize the eggs of many females. The floating eggs are released over the reef during an afternoon ebb tide, which carries them out to sea, away from reef predators.

The larvae develop within a day of hatchi,ng and feed on plankton, Currents carry them back to the reef lagoon where they grow to maturity.

Right: A mucus sac protects the fish from nighttime predators.

Above: Parrotfish swim with the tide in schools of up to 40 while grazing the coral reefs.

I DID YOU KNOW? • Parrotfish are noisy feeders, often audible to divers swimming over a reef. • Parrotfish use the sun's position to find their way. On sunless days their navi­gation is much less efficient.

~ FOOD &: FEEDING The parrotfish is named after the way its front teeth are fused into a powerful parrot­like beak. This is an ideal tool for scraping algae from the dead coral rock between the living coral colonies.

Left: The parrotfish's beaklike front teeth chip away at coral.

Far left: The parrotfish both scrapes the coral and bites off whole chunks.

• Feeding parrotfish can raise a "dust cloud" as they scrape at the reef. • Regular feeding routes are marked by heaps of coral dust excreted by parrotfish.

A parrotfish feeds by swim­ming head down and bump­ing the rock surface with its mouth, scraping off a mouth­ful of algae at each bump. The algae grows back each day, replenishing the food supply.

A parrotfish also bites off whole chunks of live coral, but whether this is to get at the animals that live in the coral or the algae on its surface is uncertain. Using flattened teeth in its throat, the fish grinds up the coral and swallows the fragments, digesting the edible parts and excreting the rest.

EUROPEAN FLOUNDER

ORDER Pleuronectiformes

FAMILY Pleuronectidae

GROUP 4: FISH

GENUS & SPECIES Platichthys flesus

The European flounder's flattened body and ability to change color to blend in with its surroundings make it

well adapted for a predatory existence in coastal waters.

KEY FACTS

SIZES Length: 20 in.

Weight: 6-7 lb.

BREEDING Sexual maturity: · 3-4 years.

Breeding season: February to

May, depending on the tempera­

ture .

No. of eggs: Up to 2 million per female.

Incubation: 11 days.

LIFESTYLE

Habit: Does not form schools, but

gathers in large numbers at the

spawning grounds.

Diet: Bivalve mollusks, shrimp, marine worms, and similar species.

RELATED SPECIES

Closely related flatfishes include

commercial food fish such as

summer flounder, Paralichthys

dentatus, and halibut, Hippoglossus

hippoglossus.

FEATURES OF THE EUROPEAN FLOUNDER

Camouflage: Upper side darkens in adulthood to mimic colors of surround­ings. Within two or three days it blends in

Range of the European flounder.

DISTRIBUTION

Found on all the coasts of Europe and the Mediterranean

from the tide line down to 175 feet, as well. as river systems and lakes accessible from the sea.

CONSERVATION

The European flounder is a popular fish with sport fishermen, but it has no commercial value and is in no danger of extinction from overfishing .

to new surroundings. - - ---------------':M.."...+1' ~r'J

fI.~71/

Eyes: The left eye shifts across the young flounder's snout to the right side by the time the fish reaches adulthood.

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Fins: Run the length of the body to help the flounder move with tidal flow.

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The European flounder is hatched

in the surface waters of the sea but may spend

much of its life in fresh water. Barely able to swim,

the fish travels upstream on the tide to feed on small

aquatic animals that live near the shore.

~ HABITAT The European flounder is one of the most adaptable and widespread of all flatfish . Al­though native to European coastal waters, it can tolerate a wide range of temperatures: it has been caught as far north as the Arctic coast of Norway and as far south as North

Africa. The flounder also has the

unusual ability to survive in both salt and fresh water. The flounder is especially common in brackish river mouths. It often moves upriver at high tide to feed in the tidal river waters. When the tide ebbs, the flounder lies stationary on the bottom of the river and

waits for the returning tide, which then carries it still further inland.

Unlike the flounder, most fish cannot live in both salt and fresh water. Aquatic animals must maintain a balance between salt con­centrations in their body fluids and the saltiness of the water they live in. Because of this, freshwater fish are un­able to survive in salt water and saltwater fish cannot survive in freshwater. The flounder is one of the few

fish that can survive in both.

Below: The flounder relies on the rising or falling tides to help it swim.

~BEHAVIOR The flounder spends most of its life on the bottoms of the ocean and rivers. It lies on its flattened side in the sand or mud. In the adult flounder, the eye that would normally be on the side of its body that is flush with the ground is repositioned on the side facing upward.

Other parts of the flounder's anatomy remain in the posi­tions that are customary for

most fish. Its pectoral fins, for example, are on opposite sides of its body. The gill covers are also on each side of the

flounder's body; one opens upward and the other opens downward. When the fish is

lying half-buried on the bottom, the expelled water from the lower gill is usually pumped out through the upper gill. The flounder can

~FOOD &: FEEDING The flounder has powerful crushing teeth in its throat that crack open the hard­shelled mollusks that make up much of its diet. It mainly eats cockles, shrimp, and marine worms.

At low tide these animals lie buried in sandy or muddy beaches, but at high tide they emerge to feed on in­shore plankton. The aquatic animals are easy prey for the flounder as it glides over the flooded beach.

Flounders that swim up­river have a more varied diet, and many feed on the swarms of tiny, threadlike elvers (young eels) that they follow upstream from the sea each year.

escape from predators by gulping water and ejecting it through the lower gill, which allows it to rise vertically from the seabed.

The flounder's main defense is its chameleon like ability to change color to blend in with its surroundings. Its top side

becomes pale when the fish is on sand, dark when it is on mud, and mottled when it is

~BREEDING Although a flounder can live and feed in fresh water, it must return to the sea to breed.

It spawns (produces eggs) on the ocean floor in water 80 to 1 30 feet deep, but the eggs are buoyant and they float to the surface. When the hatchlings emerge, they stay in the surface waters and feed on tiny floating organisms

Right: The adult floun­der's left eye has shifted to join the right eye, and the once straight mouth has twisted vertically.

on gravel. Because the change in coloration takes

several days to complete, the

and then gradually move toward shallow water.

A newly hatched flounder has an eye on each side of its snout. As the fish matures, the left eye usually shifts right, next to the other eye. The side with the two eyes changes to a darker color. The fish then sinks to the bottom and lies on its left side, with its eyes facing up.

flounder disguises itself by digging into the bottom and covering itself with sand or gravel.

The flounder rarely swims; instead, it moves with the

current. It can swim if it must by undulating its body up and down. Its frill-like dorsal and anal fins provide extra momentum.

DID YOU KNOW? • Sometimes a flounder's right eye shifts to its left side. This fish lies on its right side.

• Adults often migrate long distances to the spawning grounds and may lose up to one-tenth of their body weight in the process.

• The sole has a characteristic not found in its relative, the flounder. Not only does one of the sole's eyes shift to join

the other on its top side, but its mouth shifts to its bottom side.

• The flounder can blend in with almost any background. When it is placed on a

chessboard, for example, it adopts a roughly checkered

pattern.

SIAMESE FIGHTING FISH

.. ORDER ~ Perciformes

FAMILY Belontiidae

.. GENUS &: SPECIES ~ Betta splendens

The Siamese fighting fish is notorious for its aggressive behavior toward rivals, but it also displays remarkably

gentle behavior, caring for its young from birth.

KEY FACTS

SIZES Length: Wild fish grow up to 21/2 in .

BREEDING Eggs: Tiny, spherical, and transpar­

ent. Laid in 3-7 batches of several

hundred. Hatching period: 24-30 hours.

LIFESTYLE

Habit: Solitary, territorial. Diet: Small insect larvae, particu­

larly mosquitoes; also aquatic crustaceans and other animal

matter.

Lifespan: About 2 years.

RELATED SPECIES

Siamese fighting fish belong to

the order of perch like fishes,

Perciformes, the largest order of

fishes in the world. The 7 species of

fighting fish are closely related to the gouramis and mudskippers.

Range of the Siamese fighting fish . ~==~==========

DISTRIBUTION

Siamese fighting fish inhabit Southeast Asia from Thailand

to Borneo. Cultivated varieties are bred in aquariums

around the world .

CONSERVATION The brightly colored aquarium varieties are selectively bred

from cultivated stocks. Wild populations are not threatened.

HOW THE SIAMESE FIGHTING FISH BREEDS

1 Before mating the male builds a nest. He blows mucus bubbles that stick together to fo rm a raftlike construction.

catches the sinking eggs in his mouth and then blows them into the nest.

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2 The male wraps himself around the female and turns her on her back. She releases her eggs and the male fertilizes them.

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4 The eggs stick to the nest. The male stands guard over them until they hatch.

0160200331 PACKET 33

Easily roused to jealous fury

by the presence of a rivat the male also

displays gentleness as he courts a female

with a graceful dance and cares for her eggs.

He protects the eggs from the female,

who may eat them after spawning.

~HABITAT Wild fighting fish live in calm waters of small lakes, ponds, slow rivers, and irrigation ditches. They prefer shallow, clear water with submerged plants under which they can hide from predatory birds. In still waters fighting fish often swim near the surface to

Right: Dur­ing courtship the male nibbles at the female's scales and may even bite at her fins.

breathe. They will suffocate if submerged too long .

The fighting fish feeds on plants, small worms, and fragments of dead animals. A voracious eater, the fish grows quickly and may com­plete its entire lifecycle in just over two years.

-

~PREDATORS The male fish fights to defend its territory or mating rights during breeding season. The male is most ferocious when attacking a rival suitor.

When he becomes angry, the male begins to glow, its flanks and fins illuminated in vibrant shades of metallic green and red. The heightened colors warn the intruder, sometimes intimidating the weaker fish into retreating.

In a fight, one fish advances

Left: The brightly colored aquar­ium varieties are selectively bred for their beauty.

DID YOU KNOW? • The male fighting fish is an oddity among fish species because he takes care of the eggs. He chases the female away from the nest after mating because she is likely to eat the unhatched eggs as he attempts to fasten them

fiercely, ramming the other in the flank, scattering scales or slitting a fin with its narrow teeth . The other instantly retaliates, and before long both fish may be badly in­jured. In uneven matches, the weaker fish normally flees after only a few minutes with damaged fins .

Captive fish are bred for their ferocity. Unable to flee, they may battle for hours until one of the fish dies.

Right: Flaunting himselt the male fish courts the female until they intertwine and breed.

securely to the raft.

• Fighting fish with long fins are more vulnerable than the short-finned varieties and are almost always de­feated because they can­not move as fast with their

long fins .

~ FIGHTING FISH &: MAN In Thailand the fighting fish has been selectively bred for centuries to enhance its ap­pearance and ferocity. The resulting fish is very different from its wild ancestors.

More colorful than the dull gray or green wild fish, the

~BREEDING The male's courtship display both intimidates rivals and attracts females. If he is un­sure of the other fish's sex, the male waits for it to re­spond; if it is a female, she folds her fins to indicate interest, whereas if it is a male, he attacks.

Before courting, the male builds a nest for the eggs by blowing sticky mucus bubbles that bind together and form a raft. The eggs

Left: The male blows mucus bubbles that bind together to form a nest.

captive-bred species have long, flowing, iridescent fins.

Known for their aggression, the fish will fight to the death. People traditionally placed large bets and pitted the fish against each other like game­cocks in a cockfight.

stick to the underside of the raft, safe from predators and close to oxygen.

After the male performs this display, he leads the female under the nest. He entwines himself around her and turns her on her back. She releases eggs into the water, which he then fertilizes.

The eggs are laid in small batches, and as they are released, they sink down through the water. The male catches them in his mouth and blows them up into the sticky nest. He guards the nest until the eggs hatch.

CARDINALFISH

ORDER Perciformes

FAM ILY Apogonidae

GROUP 4: FISH GENUS Apogon and other genera

Cardinalfish are small, brightly colored fish that live mainly in temperate seas and in the warm, tropical

waters around coral reefs.

KEY FACTS

SIZES

Length: Up to 7 in., depending on species.

BREEDING Sexual maturity: Not known. Spawning season: Throughout the summer. Exact time depends on location.

No. of eggs: 150-22,000, depending on species.

LIFESTYLE

Habit: Many species form large schools, while others are solitary, living on a host and coming out at night to feed . Diet: Tiny marine animals, larvae, fish eggs, and crustaceans. Lifespan: Not known.

RELATED SPECIES Cardinalfish are related to more than 8,000 other species of the order Perciformes, which also includes mackerel, tuna, and swordfish.

FEATURES OF CARDINALFISH

Body: Genera"y short and deep in a"

Range of cardinalfish.

DISTRIBUTION

Found in tropical seas throughout the world and in the Mediterranean. A few species live in freshwater streams on tropical islands.

CONSERVATION

The population seems to be stable, but it may become depleted because cardinalfish are becoming increasingly popular in home aquariums.

Color: Often red or patterned with red . Some species are black, silver, or yellow with stripes, wide bands, or spots.

same size and shape as the anal fin , which has two spiny rays :

Head: Large with prominent eyes and large mouth con­taining sma", pointed teeth .

Cardinalfish are usually bright red or marked

with red patterns, but they can also be black,

silver, or yellow. Several species produce

an artificial light called bioluminescence.

These fish are popular in home aquariums.

Cardinalfish are shy. Many species hide during the day and come out at night to feed. Other species, however, form large, active schools.

Several species have a close relationship with other sea animals. An example is the tiny Astrapogon stellatus cardi­nalfish, found in the Caribbe­an and along Florida's coasts. During the day it hides in the shell of a giant conch or in the inner cavities of a sponge to avoid predators. This re-

~ FOOD &: FEEDING

Cardinalfish feed on tiny ma­rine animals and fish eggs. Some species eat small crus­taceans such as shrimp.

Cardinalfish that have a

lationship is not considered symbiotic (mutually beneficial to each species) because the conch or sponge does not appear to benefit from it.

By contrast, the Siphamia versicolor, an Indian Ocean species, has a symbiotic rela­tionship with long-spined sea urchins. It swims between the spines to clean the urchin's skin. At the first sign of dan­ger, the urchin spreads its spines so the cardinalfish can

hide among them.

symbiotic relationship with a host such as a sea urchin may supplement their diet with parasites that they remove from the host.

~ BREEDING Cardinalfish breed in summer, and most species are mouth­breeders-they carry their eggs in their mouths. The female lays her eggs in a single mass, and the male takes them into his mouth until they are ready to hatch. He then spits them into the water.

In one species the eggs are fertilized by the female . She inserts her genital organ into the male and removes the sperm for fertilization. In this species the male alone looks after the eggs. Cardinalfish that are not mouth breeders lay their eggs in abandoned shells.

Left: A school of cardina/fish shelter under a stag horn coral.

Right: The Mediterranean cardinalfish is bright red.

I I ~~ : SPECIAL ~ ADAPTATIONS

Several species of card inal­fish produce an artificia l light called bioluminescence. The reason fo r this adapta­tion is not yet clear. It is thought that the light helps cardinalfish find and attract nocturnal prey, avoid pred­ators, and communicate. About 1,500 fish are known to produce this light.

One species of cardinal­fish, Apogon ellioti, has a large population of lumi­nous bacteria in a gland near its throat. The gland reflects the light into trans­parent muscles under the throat. The muscles act like a lens, concentrating the light into one beam .

DID YOU KNOW? • The brownspot cardinalfish has an unusual defense pos­ture. When threatened, it flops over and "plays dead" until the danger passes.

• Many species of cardinal-

fish have descriptive com­mon names such as "pajama fish" and "flame fish."

• Scientists studying a spe­cies of cardinalfish in Hawaii collected more than a thou-------

... CARDINAlFISH &: ~ MAN

People have not been a great threat to cardinalfish because all the species are too small to be caught for food . But cardi­nalfish are in danger from ocean pollution and the de­struction of their habitat.

Many species of cardinalfish are popular in home aquar­iums. These species include Apogon endekataenia, which is a typical bright red color; A. margaritophorus with silver and red stripes; and Sphaer­amia orbicularis from the Pacific Islands.

Like most other tropical fish, ca rdinalfish are not protected by law. Some species may become scarce if the demand for specimens outstrips the numbers that can be safely removed from the sea.

Above: The marking of the ring­tailed cardinalfish is distinctive.

sand live specimens from one small area of reef.

• When a giant conch is taken from the sea, it opens its mantle cavity and releases cardinalfish.

Below: Silver striping is another variation in coloring.

ATLANTIC SALMON

ORDER So/moniformes

FAMILY So/monidoe

GENUS &: SPECIES So/mos%r

The Atlantic salmon's lifecycle takes it from fresh to salt water and back again. Spawned in inland waters, the young fish

swims out to open sea to mature. Eventually it returns to the same stream to mate and then die.

KEY FACTS

SIZES Length: Mature salmon are usually

1'/2-3 ft. long. Some grow to 5 ft . Weight: Up to 80 lb.

BREEDING

Spawning season: Usually November to December.

Eggs: Spherical, orange, '/4 in.

across, laid among gravel.

Hatching time: 3 months.

LIFESTYLE

Habit: Active predators in sea;

gather in schools . Range of the Atlantic salmon.

DISTRIBUTION Diet: Insects and other small animals in rivers when young;

small herring and sand eels when

in the sea.

Coasts and river systems of northern Europe from the Bay of Biscay to the Arctic Ocean; in the North Atlantic off

North America extending to Greenland.

Lifespan: 8-10 years average.

RELATED SPECIES Close relatives include several

species of Pacific salmon, trout,

and char.

CONSERVATION

Salmon are threatened by overfishing, river pollution, and

barriers that block access to spawning streams. Modern fish farming may ease the pressure on wild stocks.

LlFECYCLE OF THE ATLANTIC SALMON

1 Eggs: 10-30,000 eggs laid , each measuring about '/4 inch.

2 Larva: Feeds on attached yolk sac.

3 Fry: After leaving its gravel nest, the fry feeds on insect larvae, worms, and other small animals.

6 Spawning: The female digs a nest with her tail, then together with the male releases sperm and eggs. Spawning lasts up to two weeks sites.

©MCMXCI IMP BV/IMP INC WILDLIFE FACT FILETM PRINTED IN U.S.A.

4 Parr: At about four inches in length, the fry becomes a parr. It preys on larger fish . Its markings change to camouflage

it for hunting .~ ..... "'r~ .. 7.~"..'

5 Smolt: At this stage the salmon turns silver and is large enough to migrate tl) the sea.

0160200291 PACKET 29

The salmon spends much of its life

at sea, preying on small fish that swarm in

the cold waters of the North Atlantic. By the time

it returns to its home river to breed it has grown

into a glittering giant that leaps waterfalls

to reach its spawning grounds.

HABITAT Salmon are among the few fish that live in both fresh and salt water. The parr (young fish) develop in the cool, clear, fresh waters of the rivers where they were spawned. As they reach maturity they form schools, move downstream, and swim out to sea to the rich feeding grounds of the North Atlantic.

A salmon parr feeds on small aquatic animals such as freshwater shrimp, insects, and snails. If food is scarce, it may stay in its home river for up to eight years. A fish spawned in richer waters grows more quickly and may leave for the sea a year after hatching. At this stage the parr is olive-colored . As it

nears the sea and its body adjusts to salt water it turns silver and is called a smolt.

Once at sea, the young salmon preys on other fish such as sand eels and young herring. The richest feeding grounds are in the north, where huge schools of small fish feed on the plankton

(microscopic aquatic life) of the Arctic Ocean.

European salmon cross the Atlantic to feed in the waters between Greenland and Canada. They may stay there for over four years before they return to their home rivers to spawn.

Right: A big salmon leaps up to 10 feet to get above a series of rapids.

~ SPAWNING In winter Atlantic salmon spawn in the shallow gravel beds of cool, well-oxygenated streams. Each female digs a nest in the gravel by beating away the stones with her tail.

Female and male swim side by side, dropping their eggs and sperm together into the nest. They cover up the

fertilized eggs. After resting, the female digs another nest and they repeat the process. This may continue for two weeks until the exhausted fish drift downstream and die.

The fertilized eggs develop into larvae, then fry. These tiny fish leave the gravel as parr, feeding on worms, in­sects, and other small ani­mals for three years or more

Left: Salmon have dark spots on their flanks until they leave their spawning grounds. i before swimming out to sea.

DID YOU KNOW? • Some male salmon parr do not go to sea; instead they mature in the streams where I

they were born. When the females return these tiny males often slip in and ferti­lize eggs before the big

males get a chance.

• Mature salmon do not feed during their upstream migration . Despite this, they still snap at the bait and lures of fisherme n. No one knows why.

When it is ready to spawn, a salmon returns to the stream where it hatched. It swims over 1,000 miles of ocean, probably using the Earth's magnetic field to navigate. Then it identifies the character­istic smell of its home stream and follows the scent until it reaches the river mouth.

Salmon often gather in large groups in estuaries while they wait for a high tide to carry

~ SALMON &: MAN

Until the 1960s most salmon sold commercially were caught in nets at the mouths of rivers . Then humans discovered their ocean feeding grounds in the North Atlantic and harvested

Left: Each larva has a yolk sac with enough nu­trients to feed it for a month. After the sac has been de­pleted, the .salmon leaves the gravel as a parr.

Below: As salmon near the sea, their bodies adapt to salt water.

them upstream. They travel up to 25 miles a day. The instinct to get to spawning grounds drives them to swim up rapids and leap up waterfalls.

The fish rest in deep pools in the river to gather their strength, but they do not feed. As a result each salmon may lose nearly half its body weight on the upstream migration. Most die after spawning, completing their lifecycle.

them in huge numbers. Their populations began to drop.

Today wild salmon are becoming increasingly rare. Their home rivers are often blocked by pollution or dams.

CA RD 29 J DAMSELFISH

'(------------------------------------------~ ORDER

Perciformes FAMILY Pomacentridae

Damselfish are lively and colorful members of the coral reef community. Found in all tropical seas, they are known

as demoiselles in the Mediterranean region.

KEY FACTS

SIZE Length: Up to 14 in . but usually

smaller.

BREEDING Sexual maturity: 2-5 years. Spawning season: Spring to summer in temperate regions; less seasonal in the tropics. No. of eggs: Up to 20,000. Hatching time: 3-7 days.

LIFESTYLE Habitat: Territorial. Some species form large schools. Diet: Plankton, bottom-living

invertebrates, algae. Lifespan: Up to 18 years in captivity. Less in the wild .

RELATED SPECIES There are 235 species within the damselfish family, includ­ing 26 species of clownfish.

Range of damselfish.

DISTRIBUTION Found in tropical and some semitropical seas extending into fresh and brackish water in some areas.

CONSERVATION

Damselfish are popular aquariym fish, but collection does not seem to be a threat so far. Habitat destruction and pol­lution are problems facing all aquatic habitats, and coral reefs are especially vulnerable.

DIFFERENT SPECIES OF DAMSELFISH

Blue damselfish, Pomacentrus caeraleus: The young live together peacefully but become more aggressive as adults.

Black and white damselflsh, Dascyl/us aruanusa: Also known as the humbug fish. Extremely territorial.

© MCMXCI IMP BVIIMP INC WILDLIFE FACT FILETM PRINTED IN U.S.A.

Young beau-gregory damselfish, Eupomacenleus 'eucosticlus: Found only in the Caribbean.

Yellowtail damselflsh, MlcrtJspalhodon chrysurus: Damselfish like this often lose their bright colors in captivity as they adjust to their new sur­roundings.

0160200421 PACKET 42

More than 200 species of brightly colored damselfish

can be found in the shallow waters of both tropical

and semitropical seas. Even though these fish are

small, they are extremely aggressive and vigorously

defend their territory against competitive species

and sometimes even against human divers.

~ HABITAT Damselfish are found in all tropical and some semitropical seas, and certain species in­habit fresh or brackish water. Damselfish are most abundant in the Indo-Pacific region.

They usually live in shallow water around coral reefs, man­groves, and beds of sea grass. Some species like the bicolor

Right: A male damselfish prepares a rocky ledge for use as a spawning site. He uses color changes and, in certain species, click­ing or purring sounds to entice the female.

damselfish occur at depths of over 250 feet. Juveniles of some species like the night major are common in tropical tide pools, while the yellow­orange garibaldi is found in more temperate regions. It feeds on small animals in the seaweed that grows in beds off the coast of California.

~ FOOD & FEEDING Some damselfish feed on zoo-plankton (tiny waterborne crus­taceans and fish larvae) as they hover above coral reef forma­tions. Many others graze on the seabed, eating algae (prim­itive plants) and small bottom­dwelling invertebrates such as shrimp and crabs.

left: During courtship rituals vibrant colors distinguish the sexes more clear/y.

DID YOU KNOW? • Damselfish make unusual purring or clicking noises that are used in courtship. The same noises are used to warn off intruders. • Juvenile damselfish may be a different color than mature fish. The young garibaldi is .

Damselfish are known for their ferocious and territorial behavior. Certain bottom­dwelling species like the three-spot damselfish can defend a territory up to 16 feet across. The territory usually includes feeding and spawning sites and a shelter for protection from predators.

A damselfish defends its

The three-spot damselfish and certain other species cultivate algallawns-thick patches of algae. They eat the algae along with the inverte­brates that colonize the lawn. These lawns also provide sites for organisms that attack and destroy coral, changing the composition of the surround­ing coral reef community in the process.

red with blue spots and fin edges. When it matures, it becomes a startling yellow­orange color. • The young of one species, Acanthochromis polyuacan­thus, feed on mucus secreted by their parents' skin.

left: Some species form schools-a spectacular sight against the reef.

Right: Tube­like coral formations provide sleeping places for damselfish.

territory against fish that com­pete for similar environments, such as butterfly fish and sur­geon fish, even if they are much larger. But it generally ignores less competitive spe­cies like bass and groupers. Some other damselfish are less territorial and live in open water in schools ranging from six to several hundred fish .

After establishing a territory, a male damselfish cleans a rocky ledge or coral su rface to prepare it for spawning. Using color changes, excited swimming movements, and, in certain species, clicking sounds, the male fish encour­ages a mature female to ap­proach the spawning site and lay her eggs, which he quick­ly fertilizes. Courtship and mating take about 10 to 20 minutes. Some males may

left: Some species of damselfish feed on algae that grow on the seabed. Invertebrates such as shrimp and crabs that also feed on the algae pro­vide another valuable source of food.

mate with several females. Each female fish lays up to

20,000 tiny oval eggs, which the male tirelessly guards and tends. He fans water across the eggs with his fins, some­times picking out dead eggs that could develop fungus and threaten the whole batch. Male damselfish defend their eggs against fish much larger than themselves with little regard for their own safety.

The eggs hatch after three to seven days, and the larvae spend weeks drifting and feeding on animal and plant plankton. Some species of damselfish mature at two or three years of age while others take much longer.

left: Damsel­fish stay close to the coral reef, often darting into dark crevices to hide from predators. Some species remain in the same colony for two years.

FAIRY BASSLET

ORDER Perciformes

FAM,ILY Serranidae

GENUS Anthias

"Fairy basslet" .is the general name for tropical members of the sea bass family. These are tiny, colorful fish that can change

sex from female to male.

KEY FACTS

SIZES

Length: Up to 5 in., according to

species.

Weight: 1-2 oz., according to

species.

BREEDING

Sexual maturity: Not known.

Spawning season: Throughout

the summer.

No. of eggs: Several thousand.

~ LIFESTYLE

Habit: Most species form large

schools; others live in small groups

under coral ledges.

Diet: Zooplankton, tiny marine

animals, crustaceans, and fish.

Lifespan: Not known.

RELATED SPECIES

Fairy basslets are related to over

400 species of the sea bass

family.

Range of the fairy bass let.

DI STRI BUTION

Coral reefs throughout the world . Large populations also

found in t.he Indian and Pacific oceans, especially near the

Great Barrier Reef of Australia .

CONSERVATION

Fairy basslets seem to thrive, but continued destruction and

pollution of coral reefs may threaten their future. Collection

for home aquariums may also endanger some species.

FEATURES OF THE FAIRY BASSlET

Dorsal fin: Raised by the male during

Pacific fairy bass let Head: Rounded. Medium-size fairy basslet f Hermaphrodite

mating display. ___ _ Adult males also have elongated dorsal spines.

Tail fin: Deeply notched. Often bordered with contrasting color.

Fairy blal,'

eyes and large mouth with -----....1 pointed teeth.

Colors: Males have vivid coloration, often magenta or ·Yellow with orange markings.

Royal gramma

@ I

Fairy basslets have a wide range of colors

and patterns. Like other coral reef fish,

the males of the basslet species are more

vividly colored than the females. They also

have more prominent dorsal fins.

~BREED ING The fairy bass let breeds at dusk, when light levels are low and the fish are least at risk from preda­tors. The male displays to the nearby mature females. He makes his dorsal fin and spines stand upright and swims back-

The fairy basslet is one of the smallest fish living among coral reefs in tropical waters. Most species gather in large groups, or schools, of young fish and mature females, with just a few adult males. When the fish are not feeding, the schools stay near the reef. Here, they can take shelter from predators.

~ SPECIAL ADAPTATIONS

Fairy basslets have no de­fense against predators. But the large numbers in the' schools provide some pro­tection for individual fish.

Members of the basslet ge­nus Anthias are hermaphro­dites; that is, an individual fish has both female and male reproductive tissues and can change sex. The ad­aptation is probably a way of ensuring survival, since it gives each fish two opportu­nities to reproduce.

All fairy basslets are proto­gynous, or female at birth, and every female has the potential to become male. But research-

ers believe that the aggressively dominant nature of the male basslets in the school might keep the females from being stimulated to change sex when it is not necessary.

The most likely times for a sex change are when one of the males dies or when a school becomes very large. Then the senior female changes into a male within a few days and can produce sperm and mate with a female.

ward and forward to show off his colorful body. One brightly col­ored species, Anthias dispar, dis­plays especially vigorously.

The male rubs against the cho­sen female's sides and belly for a few minutes. Then the pair swims rapidly toward the surface of the water, away from the reef. As they reach the surface, the male releases his sperm, and the female releases thousands of eggs. The sperm and eggs drift together into open water, away from the many reef predators. The pair then dives quickly back to the shelter of the reef. This method of breeding is called pair spawning.

Left: A goby basslet.

Right: The royal gramma is one of the smallest of the fairy basslets.

Below: Fairy bass lets leave the reef to feed.

... FAIRY BASSlET &: ~ MAN

Many species of fish from coral reefs around the world are now being included in home aquariums. The fairy basslet is among those now being widely collected.

The most popular fairy basslet species include Anthias squami­pinnis, a bright orange fish with large, delicat~fins; A. huchtii, which is yellow, with bright blue and red stripes; and the rare A. pleurotaenia, sometimes called the "purple blotch anthias." Be­cause of their growing popular­ity, local populations may be­come depleted.

DID YOU KNOW? • Many fairy basslet species have colorful common names. For example, Anthias squamipinnis is also known as "wreckfish," "jewelfish," and "lyre-tailed coralfish." • The Caribbean jewelfish, which weighs up to 700 pounds, and Gramma loreto, at less than one ounce, are both members of the Serranidae family. • Larger members of the sea bass family can be fierce predators. The Queensland grouper sometimes stalks shell and pearl divers and has even been known to at­tack them.

Below: A black cap basslet feeds at the edge of a coral reef.

~ FOOD &: FEEDING The fairy basslet feeds mainly on plankton (microscopic crus­taceans and larvae that drift in the ocean), although the larger basslet species may also catch tiny marine animals and fish.

Large schools of fairy basslet swim out from the protection of the coral reef and travel through the water looking for plankton. They frequent the outer reef slopes and lagoon passes, preferring clear water with an active current that is a rich source of plankton.