Marine Fishes

Phylum= Chordata Evolved- 530 million years ago Ancestors are tunicates and

lancelets

All Chordates are characterized by:

1. Pharyngeal gill slits 2. Dorsal Hollow Nerve Cord 3. Notochord 4. Tail lying posterior to anus

Habitats range from the intertidal to the deepest

trenches.

Why are fish commercially important?

1. Human nutrition 2. Fertilizer 3. Recreational fishing

Why have fish populations declined?

1. Destruction of habitats 2. Pollution of Coastal Waters 3. Overfishing

90% of all of the world’s fisheries will be depleted

by 2050.

Craniates Have a cartilaginous bone or

shell.

What were the earliest vertebrates

like? Fish that lacked both jaws and paired appendages.

Where do you think they lived?

Seafloor Scavengers

Six Groups of Fish!!!!!!

1. Hagfish 2. Lampreys 3. Sharks and Rays 4. Ray finned fishes 5. Coelacanths / lobefins 6. Lungfishes

Hagfishes Lack vertebrate No scales Small brain, eyes, ears, and nasal

openings that connect with the pharynx and slime glands

Slime eels 70 species, females outnumber 100 to 1 Produce milky slime when disturbed ->

protection -> so much it coats the gills of the other fish and suffocates it.

Used for their leather qualities (high demand)

Skulls made of cartilage and lack jaws and a vertebrate

Dental plates grasp prey and latch onto flesh

Bottom dwelling scavengers

Lampreys 38 species, parasitic feeders The skeleton is made of cartilage

that contains no collagen and they lack jaws

Oldest living lineage of vertebrates Oral disk and rasping tongue with

horns to grasp prey, literally puncturing a hole in the body and sucks the organs and tissues out.

Anadromous-> migrate from SW to FW to spawn. The males build a nest out of stones and the females come along and attach themselves to the stones. The male attaches itself to the back of the female-> male sheds sperm-> adults die-> larva hatch-> migrate and hide in the river bottom-> live for 7 years and then go back to the sea to lay eggs and die.

Sharks and Rays= Cartilaginous fishes

•Class Chondrichthys•Skeletons are cartilage

•Jaws, paired fins, sandpaper like placoid scales

•970 species

Sharks and Rays

Top predators Highly specialized Whale sharks, basking

sharks, and megamouth sharks = zooplanktivorous -> filter feed small planktonic animals.

Whale Shark

Basking Shark

Megamouth Shark

http://www.youtube.com/watch?v=RxhqBmnZv8Q

Carnivorous Greatest # inhabit temperate and tropical

waters Swim with sideways sweeps of their

caudal tail fin Heterocercal – dorsal portion is longer

than ventral.

Pelvic fins of males -> claspers-> transfer sperm from the male to the female.

Ventral mouth with lots of rows of teeth-> always replaced and the nonfunctional inner rows move forward to replace.

Upper jaw / teeth slice through the prey’s flesh and tear (30,000 teeth in a lifetime).

Swallow food whole because their jaws don’t move back and forth.

Exploited for fins, meat, oil, leather, cartilage, and sport

Shark fin soup

Skates and Rays

Flattened bodies Spiracle on the top of the head ->

water is drawn in through spiracles and passed out over the gills. An aeration system prevents the gills from getting clogged with sand.

Crush prey except for manta rays-> feed on plankton.

Eagle rays / manta live in open water, others are bottom feeders.

Eagle Ray

Defenses -> stinger. Electric rays have electric organs in head= 220 volts that they use for navigation and stunning of prey.

Venom (skates don’t have a stinging spine)

Sawfish and guitarfish -> series of barbs along snout-> shake head / “saw”

Skate wings= scallops

Compare / Contrast

Skates:› Swim with wave

action› Fleshier tails› No venom› Leathery egg

case called a mermaids purse.

Rays:› Swim by moving

fins up and down like a bird

› Streamlined tails with barbs and venom

› Give birth to live young

Ray Finned Fishes

26,000 species- most numerous Characterized by their swim bladder, fin

rays, bony skeleton, bony scales in skin, terminal mouth, operculum that covers the gills and protects them.

Divided into two groups!!!!

Heterocercal tails Marine sturgeons Cartilaginous

skeleton Ganoid scales (thick

/ heavy)

Homocercal tail Cycloid and Ctenoid

scales Maneuverable fins

Medium fins-> one or more dorsals for stability

Paired pectoral / pelvic fins -> steering Ex- Chinook salmon, bass, trout, grouper

Coelacanths Lobe finned fishes Thought to be extinct until 1938 when

fisherman discovered them in the West Indian Ocean.

Thought it was extinct 60 million years ago http://www.youtube.com/watch?v=ZQMm5HN1Ums

Living fossil Before this they were only known as

fossils that were 400 million years old 2nd one caught in 1952- Madagascar /

Africa Natives eat it regularly -> dry and salt it

and eat its flesh and use its skin for sandpaper.

Little is known› 6ft in length› Large blue scales› Feeds on fish and squid› Stand on fins› Rotate fins 180 degrees

Lungfishes The second lineage of living lobe-

fins All are found in the Southern

Hemisphere Only found in fresh water,

generally in stagnant ponds and swamps

Can gather oxygen from both the air through their pharynx and the water through their gills.

http://www.youtube.com/watch?v=tqWciuuKn3c

Fins-> Stiff rays covered by skin. Dorsal= stability Ventral= stability Caudal= propelling Anal= stability Pectoral= locomotion / side to side

movement Adipose= stability (2nd dorsal)

Skin Slime cells are going to aid in

protection against bacteria, etc.

Scales Lie in dermis and overlap for protection

(armor) Placoid-> similar to teeth (sharks, rays->

sandpaper) Ganoid-> flat, cover fish with little

overlapping (GAR and many bony fishes) Cycloid-> oval shaped with growth rings

(carps) Ctenoid-> spines cover one edge (cichlids)

Placoid

Ganoid

Cycloid

Ctenoid

Gills Located under gill slits (5 slit

opening) Tissue between the slits on each

side= gill arch. 5 gill slits and 4 gill arches= gills

are mounted

Lateral Line Connected to sensory cells / nerve fibers Line is from gills to tail fin Detect minute electrical currents in the

water, echolocation Function-> Schooling

http://www.youtube.com/watch?v=N3CXUO0jxNQ

Swim Bladder= Buoyancy!!!!! And it is a gas

filled sac that offsets the density of their bodies.

Fish have to constantly swim if they want to stay afloat!

What happens when a fish descends?

More gas must be added to the swim bladder or bladder will compress and the fish will become denser and sink.

Ascends-> Removes gas= when arise too quickly the swim bladder comes out of their mouth.

Fish that lack swim bladders…

Mackerels, sharks, skipjacks, scorpion fishes, deep sea fish-> have to keep swimming or they sink.

Body Shape!

!!!Correlates with its

habitat

Fusiform Body Shape

• Very high and narrow tail= Fusiform body shape

• Which allows them to move through the water with great efficiency and speed.

• Examples-> sharks, tunas, marlins

Laterally Compressed

Helps them navigate / swim through tough spots, especially coral reefs.

Ex- Butterfly fish, Angelfish, Sea grass fish

Bottom Dwellers Flounders Depressed / flattened body. Flounders begin life looking like

a normal fish but during their juvenile stage they begin to swim on their side and eye migrates from the bottom side to the upper side.

Globular Bodies Enlarged pectoral fins to

support round body. Ex.- Anglerfish, Oyster

toadfish, scorpion fish

Fish Coloration and Patterns

Colors serve as many functions:› Camouflage› Communication› Conceal themselves from prey› Attract mates› Warn other fish that they are poisonous

Two Basic Types!!!!

1. Pigments (Biochromes)

2. Structural Colors

Chromatophores Cells where the pigments are found in the

center of the body cell. These allow fish to change colors to match

their surroundings. Darkness depends on how much of the

pigment is dispersed throughout the cytoplasm.

Not all chromatophores contain the actual pigment color that they appear. Some work on different principles other than selective absorption/reflection.

Chromatophore

Pigment Type Colors

Melanophore-> Most common

Melanins ColorDispersed= darkerContract= lighter

Black and Brown

Xanthophore Pteridines and Carotenoids

Color Red and orange

Erythrophore Pteridines and Carotenoids

Color Orange and yellow

Iridophore Guanine and other Purines

Refelctive White, Silver, Blue, and others

Epidermis

Slime Cells

Dermis

The xanthophore or filtering layerThe iridophore or reflecting layerThe melanophore or absorbing layer

Fish can alter their color by moving pigments around. For example, the flounder can alter its body pattern and color to match its immediate environment.

http://www.youtube.com/watch?v=kOembW28AGw

http://www.youtube.com/watch?v=Hc8Gcxuj3lI

What are the most common pigments found in fish?

Melanins Carotenoids Iridophores

Structural colors are produced:

By light reflecting from crystals in specialized chromatophores called iridophores.

Obliterative countershading

Dark colored back that fades to a pure white belly.

Examples Sharks-> when viewed from

the top the dark blends in, from the bottom it’s the same thing.

Tuna Marlin

Disruptive Coloration

Where vertical lines and eye spots interrupt the background color of the body.

Ex- butterfly fish-> eyespot confuses predators

Red Drum

Why is disruptive coloration beneficial?

Breaks up the pattern and makes it more difficult for predators to see.

Poster Colors Very bright, elaborate patterns

that may advertise territorial ownership, allow schools to stay in contact, or sexual displays.

Warning / Aposematic Coloration

Bright colors that advertise to predators that I’m dangerous / poisonous to eat.

Lionfish, stonefish,

Cryptic Coloration

Blend in with the environment. Camouflage themselves to

avoid predators and ambush prey.

Example- Scorpion fish- looks like rocks

Ex- Pipefish- mimic sea grass

Videos

http://www.youtube.com/watch?v=KOJhIl-qlWY

Locomotion

Fin Walkers / Crawlers

They possess a strengthened girdle with extra muscles to facilitate their walking, which is done using their pectoral fins with tail supporting the end of the body.

They are able to climb tree roots and surface for long periods of time out of the water. They use their unusual ability to hunt down terrestrial insects and surface dwelling crabs.

Burrowers Hide or bury themselves into the sand

for protection from predators, habitat and finding prey.

Gliders Gets its power and speed from its

caudal fin by moving it from side to side with powerful strokes.

They swim very fast near the surface of the water and if a predator is near, they will reach speeds of 15-20 mph and then break the surface of the water.

Videohttp://www.youtube.com/watch?v=OmWRCdUw17E

Swimmers Swim normally by using

their pectoral fins that would be comparable to our arms.

Current Swimmers Some fish just ride with the current to

save on energy while some swim against it like salmon

Respiration and

Osmoregulation

How do fish breathe?

Use gills to extract oxygen from water and eliminate carbon dioxide as an aid in maintaining proper salt balance.

Blood Flows…………..

In the opposite direction from the incoming water creating a countercurrent multiplier system, which maintains a stable gradient that favors the diffusion of oxygen into and carbon dioxide out of the body.

Countercurrent= blood in the capillaries flows in the opposite direction of water.

Low-oxygen blood enters the capillaries and doesn’t encounter water until it reaches the end of the gills, which is low in oxygen. As blood travels in the direction opposite to the water, it encounters "fresher" water with higher oxygen concentrations. Then along the capillary, a steep diffusion gradient favors transfer of oxygen into the blood.

Why must water continuously pass over

the gills? To keep the blood oxygenated

How do ray finned fishes ventilate their

gills? 1. Water enters the mouth 2. Mouth cavity contracts and the

chamber surrounding the gills pushes the water across the gills.

3. Gill chamber contracts and the water is released from the operculum (moveable flaps of the tissue that covers the gills).

Ram Ventilation Ventilate their gills by swimming at

high speeds with their mouth open. Ex- sharks, tuna, swordfish.

Osmoregulation When an organism maintains the

proper concentration of solutes and water in its body fluids.

Rectal gland= excretes Ray finned fishes compensate for water

loss by drinking water, removing the salt using the gills, and keeping the “freshwater.”

Ray finned Fishes vs. Cartilaginous Fishes

Lose water by osmosis (movement of water across a semi-permeable membrane.

Gains salt by diffusion (movement from areas of high to low concentration).

Excretes salt through the gills through specialized chloride cells.

Very little water is lost in urine.

Kidneys have small or no glomeruli (tufts of capillaries that filter blood from the urine)

Produce a small volume of ISOTONIC urine.

Gain water by osmosis, salt diffuses in through the gills.

They do take some salt in from food.

Kidneys with large glomerulli which re-absorbs urea.

Have lots of urea and TMAO (trimethylamine oxide- metabolic enzyme)

Salt excreting gland in the anal area.

Excretes a large amount of hypotonic urine.

How do sharks solve the problem of losing too much water via osmosis?

Retain urea and TMAO in their blood as well as the body fluids that balance the solute concentrations of the saltwater.

How are bull sharks able to enter

freshwater safely? Reduce the levels of

nitrogenous waste in their body fluids by excreting it through their rectal gland.

How do ray finned fishes compensate for the loss of water?

Drink seawater, remove excess salt, retain water, and the specialized chloride cells on the gills eliminate salt.

Sharks sink in seawater if they stop swimming, therefore how do they compensate for this?

Large quantity of squalene in their livers.

Squalene= oily material, density is less than seawater.

Allows to offset sharks density.

Nervous system= Brain,

spinal cord, nerves, and

sensing receptors

Explain the intricate olfactory system of the hammerhead shark.

Has a nostril on each tip of its nose “hammer” and as it swims it moves its head from side to side, increasing its ability to smell. When the smell is equal in both nostrils that’s when they know the prey is dead ahead.

The Lateral Line System

Two canals that run the length of the body.

Vibrations in the water cause the fluid in the canal to move cupula which then sends a signal to the animals brain.

Function= locate prey, schooling, and avoid predators

Neuromast Cell Organ

Sensory receptors in the lateral line that detects vibrations.

Fish Ears Regulation / balance membrane sacs

(three layers) and they have otoliths (ear stones) which work with the maculae / sensory receptors where sound is detected through vibrations of maculae and otoliths.

What fish possess a third eyelid called a nictating

membrane? Sharks-> used for

protection Monocular vision-> each

eye sees its own independent field

Ampullae of Lorenzini

Sharks sense electrical currents in the water by scattered organs that are over the top / sides of their head.

May use to sense prey.

Why do many carnivorous fish

swallow their food whole? If they were to chew it,

then they would block the water flowing over their gills.

Feeding Strategi

es

Puffer-fish and Boxfish

Crush prey with jaws

Butterflyfish Tiny mouths and they feed on little krill

and coral polyps

Groupers Wait for prey on the bottom,

motionless -> springs up and grabs the fish

http://www.youtube.com/watch?v=dU-DizDMJQg&feature=related

Flounders Camouflaged on the bottom,

motionless-> spring up and grab fish

http://www.youtube.com/watch?v=GbcdeI7psUc

http://www.youtube.com/watch?v=o5z0jusJukM&NR=1&feature=fvwp

Parrotfish Scrape algae off rocks with beaklike

mouth

Several fish take shelter in the crevices and holes of coral reeves (sing: coral reef).Corals are found in shallow warm seas all over the world. In the Caribbean waters, lives a fish called, Parrot fish. It builds cocoons in the reef crevices.

Parrot fish is beautifully colored. Its mouth is drawn in the form of a beak that resembles the beak of a parrot. Hence, the name.

Parrot fish feeds on algae that are found growing on the coral reef surface. The fish scrapes the algae with its strong beak. By feeding on the algae, the Parrot fish protects the coral reef from algal attack. The coral reef is the home of the Parrot fish.

During day time, Parrot fish join other fishes and swim away from coral. When the night falls, the Parrot fish returns to the reef. It searches for a safe hiding, where it can sleep and spend the night...

After finding a suitable crevice, the Parrot fish builds a cocoon nest. It is a mucous cocoon. Mucous is a sticky substance secreted by the skin of the fish. The mucous cocoon of the Parrot fish is transparent. It masks the scent of the fish and protects from predators, while the fish is asleep.

If however any predator disturbs the cocoon, the Parrot fish will wake up from its sleep and move away in swift action. The mucous cocoon is shattered. It forms an opaque cloud in front of the predator which is left confused leaving enough time for the Parrot fish to escape...

In the morning when the sun rays light up the waters, the Parrot fish wakes up from its sleep. It leaves its cocoon nest.

The Parrot fish uses the mucous coon as its sleeping bag. Every night it builds a new sleeping bag cocoon. It sleeps at different places in the coral. It does not use the same bed or the same sleeping bag!!

Whale Shark Filter feeds using gill rakers

http://www.youtube.com/watch?v=uQrBwN39LJI

Gobies Suck up bottom sediment

Adaptations to avoid predators

Pufferfish / Porcupine fish = swallow air and blow up

Flying Fish= use large pec fins to glide out of the water

Surgeonfish= razor sharp spines on side and the tail flips out like a switch blade

Scorpionfish= Venom glands in dorsal, anal, and pelvic fins

Reproduction The path of sperm and eggs is

different for each type of fish: Three modes:

› Oviparity› Ovoviviparity› Viviparity

Oviparity Eggs are shed into the water and

embryos develop outside the mothers body.

Examples-> Whale sharks, bullhead sharks, skates, Zebra shark, horn shark

Ovoviviparity Internal fertilization and eggs hatch in

mom uterus and are nourished by yolk sac.

Sand tiger, basking sharks, thresher sharks, rock fishes

Viviparity Young attach to uterine wall or uterus

and feeds off uterine milk. Ex- hammerheads, surf perches.

Reproductive Strategies

Pelagic Spawners-> commercially important fish.› Cod, Tuna, sardines, parrotfish, wrasses› Release vast amount of eggs into the

water› Advantage= widely distributed offspring› Disadvantage= high mortality rate

Benthic Spawners Live closer to shore and produce eggs

that are generally larger than those of pelagic spawners and have a large amount of yolk.› Non-bouyant eggs› Eggs spread over rocks and sea grasses› Large number of eggs

Brood Hiders Example are Grunions

› Hides its eggs- no parental care. They swim ashore at high tide / full moon, burrow into the sand and deposit eggs.

› Males curl around the buried females and fertilize the eggs as they are laid. The eggs stay in the sand until the next high tide when they are washed to sea.

http://www.youtube.com/watch?v=0MmJKUSsQyI&feature=related

Guarders Care for their offspring until they

hatch and often through the larval stage.› Males guard offspring-> few days

til 4 months old.› Damselfish, blennies, gobies› Territorial

Bearers Female lays eggs in the mouth

of the male and he incubates them until they hatch.› Jawfish› Spit them out to aerate and rotate and then such them back in.

http://www.youtube.com/watch?v=YNmnnnAe-RM&feature=related

Hermaphrodites Organisms have both testes and

ovaries at some point in their life.› Synchronous= functional gonads of both

sexes at one time› Sequential= changing from one sex to

another› Protogyny= change from females to males› Protandry= change from males to female.

Hamlets- synchronous hermaphrodites Cleaner Wrasse- sequential

hermaphrodite Clownfish- protandrous sequential

hermaphrodites

http://www.youtube.com/watch?v=6lp87hrb-5I&feature=fvsr

Schooling 101 Group of individuals – highly organized Behavior = shoaling -> social reasons Increase efficiency in finding food

(more eggs) to detect predators Reproduction -> keeps sperm and eggs

closely together. http://dsc.discovery.com/videos/superswarm-fish-vortex.html

http://www.youtube.com/watch?v=X_urruBqlQo

Fish Migrations Daily / seasonal Feeding / predator avoidance Spawning, change in temperature Tuna- winter in California / Oregon and

Japan in the summers Mullet- FW or estuaries Catadromous-> move from FW to SW to

spawn Anadromous-> move from SW to FW to

spawn

Freshwater Eels Best known catadromous fish In the fall the adults migrate down coastal

rivers to the sea and they change color from a dull olive to a silver and their eyes get larger.

Take 2 months to reach the Sargasso Sea where they spawn

Take about 1 year to make this journey Spawn 900 ft. down-> adults die after

reproducing

Hatchlings develop into leaf like leptocephalus larvae and start to migrate back to the rivers of Europe (takes 3 years) and North America (takes 1 year).

When they reach the coastal rivers they metamorphosis into juvenile eels called “elvers” -> they migrate into streams and estuaries.

Males remain in FW to 4-8 years Females reach sexual maturity at 12

years Will return to the breeding grounds of the

Sargasso Sea.

Salmon Anadromous Pacific and Atlantic Pacific-> die after their journey /

spawning Atlantic-> return multiple times Salmon lay their eggs in shallow

depressions called redd. Develop into alevins (newly hatched)->

Parrs (1-5 years)-> smolts (5+)

Return to their native stream when it is time to spawn again-> some say that they find their native stream through olfaction (smell chemicals in the soil)

“imprinted” with odor knowledge Pheromones released by smolts Populations have been reduced due to

pollutants, dams, human activity

Crazy pics!!!!!