Chapter 7: Non-Bony Fish

Classification

Kingdom	Animalia
Phylum	Chordata
Class	Agnatha - Jawless Fishes Chondrichthyes - Sharks and Rays
Order	Agnatha Petromyzontiformes - Lampreys Myxiniformes - Hagfish Chondrichthyes Rajiformes - skates and rays Squatiniformes - angelfish sharks Pristiophoriformes - sawfish sharks Squaliformes - dogfish sharks Carcharhiniformes - ground sharks Lamniformes - mackerel sharks Orectolobiformes- carpet sharks Heterodontiformes -bullhead sharks Hexanchiformes - frilled and cow sharks Interactive journey through the shark classification

Class Agnatha (Jawless Fishes)

Hagfish - Also known as slime eels, hagfish are indigenous to both the Atlantic and Pacific oceans, where they live at depths of 100 to 3,150 feet. Eyeless, jawless, and dependent on their sense of smell to find food, hagfish invade feeble or dead fish by entering through their mouths and settling in their stomachs, where they secrete a slimy substance that protects them from the digestive juices of their hosts. They then eat their hosts from the inside out. Text and picture from: pbs.org Also you might check out a Video Clip of Hagfish .

Lamprey - Lampreys live in both freshwater and marine environments worldwide, usually migrating from saltwater to freshwater to spawn. Some sea lamprey populations have become landlocked and represent serious pests to fishing industries. Adult lampreys parasitically attach themselves to other fish, sucking out their body fluids after scratching a hole with their sandpapery tongues. Lampreys have an anticoagulant in their saliva that keeps the blood of their host fluid, and some lampreys eat flesh as well. Their unwilling hosts may eventually die. Text and picture from: pbs.org. Also you might read about Sea Lamprey Parasitism in the Great Lakes

Class Condrichthyes (Cartilaginous Fish)

Sharks and Rays:

All members of the class Condrichthyes have a skeleton made of cartilage. This is useful because cartilage is lighter and more flexible than bone. Since Condrichthyes lack the air bladder of their bony fish cousins, this helps with buoyancy. Almost all sharks and rays have a movable jaw and well developed teeth. Placoid scales also give them skin that is rough and abrasive. They have well developed pectoral fins that aide in swimming and mouths on their ventral (bottom) side. Rays are characterized by their kite-like body and mouth located on their underside.

"Once, more than 400 million years ago, the two groups shared a common ancestor that swam through the planet's oceans long before the first dinosaur appeared. Today, to the untrained eye, that common origin isn't obvious, because most sharks and rays look so different from one another. But the fish are, in fact, relatives with structural similarities. Instead of bones, their body frames are made of cartilage: the tough, fibrous tissue that gives our noses and ears their shape. To read more go to... Secret life of sharks and rays

Special Adaptations of Sharks and Rays

Ampullae of Lorenzini - Tiny pores on the ventral side of a sharks snout (seen in the picture). These pores sense tiny electrical pulses that are created by the muscle movements of other fish.

Lateral Line - Similar (in some respects) to the ampullae of lorenzini, the lateral line is a row of pressure sensitive pores that run the length of the sharks body. The lateral line allows the shark to orient to particle movement or sound. It consists of structures called neuromasts which are located in canals that lie just below the surface of the skin or the scales.

Sharp Skin - Sharks and rays also share the same kind of skin: instead of scales, they have small tooth-like spikes called denticles. The spikes can be so sharp, in fact, that carpenters have long used shark skin as sandpaper!"

Teeth - "Teeth, often an identifying characteristic, vary in shape and configuration according to diet and feeding habits. Those huge, triangular teeth familiar from Jaws have serrated edges that equip the white shark for cutting into a fare of seals, sea lions, porpoises, even sea turtles. To read more go to...Shark FAQ's

Diversity

Animal Diversity Web - Shark Species List

Shark Species List - PBS.org

Who's who of sharks - PBS.org

Ray Species (sharks too) -SEASKY.org

Three hundred fifty species of sharks are identified worldwide, including 73 species known to inhabit U.S. Atlantic coast, Gulf of Mexico, and Caribbean waters. What identifies them all as sharks is the combination of paired fins, including pectoral fins whose rear edges are free rather than attached to the head; five to seven gill slits; and rough, sandpapery skin.

Shark Conservation

Sharks are especially vulnerable to habitat destruction and fishing pressure because they have slow rates of maturation and reproductive turnover. Sharks are unusually long lived and give birth to relatively minuscule numbers of young when compared to other types of fish. Many species breed only every other year and have 13 month gestation periods.

Sharks are often caught as bicatch in longlines or drift next. However for the last 30 years sharks have been increasingly targeted specifically. Sharks can be eaten (some are very tasty), but most are targeted specifically for their fins. Shark fin soup is a very popular (and very expensive) dish served in many Asian countries.

Questions to Research:

With no jaws, explain how lampreys and hagfish eat.

Draw a simple sketch of a shark and label all of its fins. For help go to: shark anatomy

Visit any of the sites in the shark and ray section. Pick your favorite (the one that is most interesting to you). Describe your favorite shark or ray and explain why it interests you.

Anatomically speaking sharks and rays are really more alike than they are different. However, they use their bodies very differently. Watch a video of a manta ray swimming and a hammerhead shark swimming. Describe the difference.

Examine the picture to the left. Then go to the Shark-O-Matic to identify what species of shark this is.

To check your answer in #4, click here to watch a video of this shark species. After watching the video, how would you describe this sharks feeding strategy?

Whale sharks and basking sharks are the largest of the sharks. Yet they feed on the smallest of prey (plankton.) Watch either video and describe in your own words what this looks like.

We often consider salmon sharks a "local species" in South central Alaska. TOPP has been actively tagging and tracking salmon sharks for the last five years. Go to the interactive map and explain where salmon sharks go after a summer spent in Prince William Sound.

Explain how the Ampullae of Lorenzini and the lateral line help sharks locate prey.