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

• 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

–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.