Phylum Chordata

-Subphylum

Vertebrata Vertebrate Chordates

General

Characteristics 1. Vertebral column, or

spine- bones or cartilage

that surround and protect

dorsal nerve cord

2. Cranium, or skull, to

protect brain

3. Endoskeleton

composed of bone or

cartilage

Class Agnatha

•Greek, gnathus,

meaning “jaws,” and a,

meaning “without”

•Jawless fishes

•Hagfishes and

lampreys

•Skin lacks plates and

scales

•Eel-like body

•Unpaired fins

•Cartilaginous skeleton

•Notochord remains

Hagfishes

•Small eyes beneath

skin

•Lack vertebrae

•All species are marine

•Body fluids are

isotonic to

environment

•Bottom dwellers in

cold environments

•Feed on small inverts and dead or dying fish

•Two plates and rough tonguelike structure pinch off chunks of flesh

•Often burrow into

body of dead organism

–Enter through gills,

skin or anus.

–Once inside, eat

internal organs

•Secrete a bad-tasting,

thick, viscous slime

from skin gland to

deter predators

•Knot-tying behavior

–Clean excess slime

–Stability and

leverage to tear off

food

Yummy

Lampreys •Most are anadromous

–Adults move from ocean to freshwater

•Opposite is catadromous

•Petromyzon marinus is

most abundant (sea

lamprey)

Lamprey Reproduction

1. All breed in fresh

water

–Usually a shallow

stream with a gravel

bottom

2. Small nest is scraped out in gravel

3. Female and male simultaneously release eggs and sperm

4. Larvae resemble lancelets

•Larvae (ammocoetes)

live in burrows in

bottom of sandy

streams as filter

feeders (3-5yrs)

•Adults live in ocean

for 1-2 yrs, spawn in

fresh water, then die

•~50% of species are parasitic

–Feed on blood and body fluids of fish hosts

•Hook-shaped teeth on oral disk

1. Oral disk attaches to host

2. Rasping tongue scrapes hole in host

3. Anticoagulant released via saliva

4. Lamprey drops off

- Host may recover,

bleed to death, or

die from an

infection

Infraphylum Gnathostomata

Class Condrichthyes

• Cartaliginous fishes

• True jaws and teeth

• Cartaliginous skeleton

• Ampule of Lorenzini

• Internal fertilization

Sub-class Holocephalii

• Ratfishes, chimeras

• Fixed upper jaw

• Scaleless

• Deep water

http://www.davidfleetham.com/

• they are characterized by:

• a gill cover over the four gills, leaving a

single opening on each side of the head;

• the palatoquadrate (upper jaw) is

usually fused to the cranium;

• no spiracle opening behind the eye;

• branchial (gill) basket mostly beneath

the neurocranium (posterior part of the

cranium that encases the brain)

•

• teeth relatively few (one pair in the lower jaw and two pairs in the upper), occurring as mineralized grinding plates; tooth plate replacement is slow;

• no cloaca, but with separate anal and urogenital openings;

• skin in adults 'naked' (without dermal denticles);

• no stomach or ribs;

• males - in addition to the pelvic claspers - have an accessory clasping organ on the head.

Sub-Class Elasmobranchii

• Super-orders

– Squatinomorphi

– Galeomorphi

– Batoidea

• Both jaws moveable

• ~800 species

Super-Order Squatinomorphi

• 6-gill sharks

• Deepwater, primitive sharks

• Angel sharks; monkfish; sand devil

• The Angelsharks are flat-bodied sharks, very

ray-like.

• They bury themselves in the sand or mud with

only the eyes and part of the top of the body

exposed.

• They have a blunt snout and are camouflaged

to blend into the sand and rocks of the ocean

bed.

• They have long, wide fins that look like wings,

giving it its name.

• It is also known as the monk shark, sand devil,

and monkfish.

• flattened body with wing-like

pectoral and pelvic fins,

• pectoral fins separate from sides of

the head,

• fleshy nasal barbels, and smooth-

edged, raptorial teeth characteristic

of the group.

• Note the weak keel on the caudal

peduncle and that the lower lobe

of the caudal fin is longer than the

upper (the opposite of most

sharks, in which the caudal fin is

decidedly top-heavy); this tail

shape may be an adaptation to

suddenly lifting off the bottom, as

when lunging after prey that

blunders within striking range.

Super-Order Galeomorphi

• 5-gill sharks

• Dominant group- 75% of all sharks

• Orders

– Lamniformes

– sqaliformes

Order Lamniformes

• Typical sharks

• 8 families

– Alpoidae

– Lamnidae

– Carcharhinidae

– Odontaspididae

– Orectolobidae

– Rhincodontidae

– Scyliorhinidae

– sphyrnidae

Family Alopidae

• Thresher Sharks

http://www.swordfishingcentral.com/gallery/ThresherSharks/thresher_shark

–Thresher sharks are easily recognized

by their enormously long caudal fins,

comprising half of the total body length.

– Threshers feed mainly on small

schooling fishes, which they corral and

stun with blows from their long, whip-

like tails. The teeth are relatively small

but razor sharp, with curved, smooth-

edged cusps, and similar in both jaws.

–Common threshers vary from coppery-

brown to bronze color above, with

metallic hues; the undersides are white.

Big eye threshers are a dark brown to a

metallic black color with paler ventral

surface. Exceptional specimens of both

types may reach 20 ft. and over 1,000

pounds.

Family Lamnidae

• “Mackeral Sharks”

– Great white

– Mako

– Salmon shark

– Porbeagle

• The mackerel sharks are large, active predators built

on a common, highly specialized body plan.

• This body plan features: a solidly-built, fusiform

body; a sharply-pointed, conical snout pocked with

large, dark eyes; a large, crescentic mouth filled

with relatively few but impressively large and

conspicuous teeth; large gill slits, extending almost

the depth of the throat; relatively tiny second dorsal

and anal fins; a narrow tail stock (properly termed a

caudal peduncle) supported by stout lateral keels;

and a lunate (crescent moon-shaped) caudal fin.

• In addition, all lamnids - to a greater or lesser extent - feature a circulatory system modified to retain metabolic heat. – This system consists of extensive networks of tightly-

packed arterioles and veinules which carry blood countercurrent to one another, allowing heat from the venous blood (warmed by muscle contraction and other metabolic activity) to transfer efficiently to the cooler arterial blood (chilled by intimate contact with the marine environment during gas exchange at the gills), thereby conserving body heat. It is a wonderfully elegant arrangement, granting these sharks the speed, strength, and endurance benefits of warm-bloodedness without the accompanying high metabolic cost.

– The functional result of all this extensive external and internal engineering is a family of high-performance predatory 'machines', capable of sustained activity in even the coldest ocean waters.

Family Carcharhinidae

• Whaler or Requiem sharks

– Tiger

– Bull

– Lemon

– Blacktip

– Silvertip

– Blue

– Silky

– Whitetip

• Distribution: global.

• Gill openings 5, the fifth behind

origin of pectoral fin.

• Small to large sharks with round

eyes, internal nictitating eyelids,

• no nasoral grooves or barbels,

usually no spiracles.

• Teeth usually bladelike with one cusp.

• Development usually viviparous with

young born fully developed. Includes

several dangerous species, but most

prefer to avoid divers.

• Etymology: Greek, karcharos, -ou =

cutting, sharp and also a kind of shark

+ Greek, rhinos = nose ( Ref. 45335).

tiger

bull

lemon

lemon

Black tip

silvertip

Blue

Silky

whitetip

Family Odontaspididae

• Sand Tigers

Distinguishing Characteristics

• Often swims with mouth open

• Two dorsal fins almost equal in size

• Caudal fin with elongated upper lobe and

prominent subterminal notch

• Juveniles have yellow-brown spots.

• The sand tiger shark has a stout body with two

large dorsal fins that are almost equal in size

and the first dorsal fin placed far back on the

trunk of the body.

• The tail has an elongated upper lobe and no

caudal keel.

• The gill slits are anterior to the origin of the

pectoral fins.

• Large teeth are arranged in three rows on each

side of the upper jaw midline. The teeth

themselves have long smooth, narrow-edged

cusps with one or two small lateral denticles.

• This shark is able to achieve neutral buoyancy and hover in the water by storing surface air in its stomach.

• The maximum length attained for the sand tiger shark is 3.2 meters (10.5 feet), although it is generally between 1.2 and 2.7 meters in length. While menacing in appearance, this shark is generally considered to be harmless.

• Range:

– In western Altantic from Gulf of Maine to Argentina. In eastern Atlantic off Europe and North Africa and in Mediterranean Sea.

• Range:

• In western Altantic from Gulf of Maine to

Argentina. In eastern Atlantic off Europe

and North Africa and in Mediterranean Sea.

Family Orectolobidae

• Nurse Sharks

• GENERAL DESCRIPTION

The nurse shark is a large, sluggish, bottom-dwelling

shark that is generally harmless unless provoked. It

has very strong jaws, a stout body, and a wide head

with obvious barbels (thin, fleshy, whisker-like

organs on the lower jaw in front of the nostrils that

sense touch and taste). The fourth and fifth gill slits

are very close together. The dorsal fins (on the shark's

back) are almost the same size and are rounded.

Behind each eye there is a spiracle, an organ that

takes in water used for breathing when the shark rests

at the bottom.

• The skin is dark gray-brown on top and some nurse

sharks, especially the young, have spots. The nurse

shark is smooth to the touch, unlike most sharks.

They are nocturnal hunters that rest during the day in

groups. Nurse sharks do well in captivity.

No one is sure how they got their name; it might be

because they make a sucking sound that is a little like

the sound of a nursing baby.

SIZE

Nurse sharks range in size from about 2-13 feet (0.75-

4 m) long. The largest are about 14 feet (4.25 m) long.