Sharks Flashcards
What class do sharks belong to?
Chondrichthyes
How many species?
~350-370
4 points about reproduction in sharks
Internal fertilization, Long gestation period, Long maturation period, Produces small numbers of relatively large young
What type of tail does a shark have?
Heterocercal
What type of “scales” does a shark have?
Dermal denticles (placoid). A tough, protective covering on skin that resemble tiny teeth. Have hydrodynamic properties that allow sharks to move with minimal water resistance.
How do dermal denticles feel?
Nose to tail, smooth. Tail to nose, rough.
Nares
External nostrils.
A nasal flap separates the incurrent from the excurrent opening. Water passes into and out of the olfactory sac, permitting the shark to detect the odors of the water.
Ampullae of Lorenzini
The patches of pores (dark in color) on the head in the areas of the eyes, snout, and nostrils.
Specialized sensory cells that are capable of detecting weak electric fields at short ranges, enabling sharks to locate prey without visual or olfactory cues.
Spriacle
Located posterior to the eye.
A rudimentary first gill slit, highly reduced/absent in most fast-moving sharks. Provides for oxygenated blood directly to the eye and brain via a separate blood vesel.
Gill slits
Located on sides, behind the mouth and before the pectoral fin.
Exit for water that has bassed through the gills. Water taken in by the mouth and spiracles is passed over the internal gills and forced out by way of the gill slits.
Claspers
Male copulatory organs.
Located on inner side of pelvic fins, on posterior end of fin.
Lateral line
Along the sides of the body, a series of small fluid-filled canals lying just beneath the skin on the head and along the sides of the body. Light colored line.
This complex system of receptors transforms underwater sound or mechanical disturbance (or change in water pressure) into nerve impulses that allows a shark to orient to the source.
First dorsal fin
First fin located on the dorsal (top) side of the shark. Can be preceded by the fin spine.
Interdorsal ridge
Space along the dorsal side of the shark between the first and second dorsal fins.
Second dorsal fin
Second fin located on the dorsal side of the shark.
Caudal fin
Tail fin. Divided into upper lobe, terminal lobe, lower lobe (heterocercal)
Caudal peduncle
Space on the body after the second dorsal fin & anal fin, and before the caudal fin
Pectoral fin
Located on sides of the body, act like airplane wings to provide lift/prevent sinking
Anal fin
Located on the ventral (underside) side of the shark, opposite to the second dorsal fin.
Pelvic fin
Located on the ventral (under) side of the shark, before the anal fin. This is where the claspers are located in males.
Cloaca
Located on the ventral side between the pelvic fins. (Right before pelvic fins in side view)
“Common exit” for waste products (urinary, intestinal, genital)
Stomach
Centrally located in the main body cavity, goes almost entire length of cavity. Three parts: cranial, fundic and pyloric.
Function: food storage and digestion
Pancreas
Located in the middle of the body cavity, underneath the middle of the stomach
A flattened white gland that secretes digestive juices and insulin.
Gall bladder
Green sac that holds bile for enzymatic digestion
