________________________________ either migrate to the sea, if marine, or remain in fresh water, where they attach themselves by their sucker-like mouth to fish and with their sharp horny teeth rasp through flesh and suck the body fluids.
__________________________________– a curious feature, since the Chondrichthyes are derived from ancestors having well-developed bone.
Sharks and Rays: Subclass Elasmobranchii
Sharks, which make about _________________________________________are typically predaceous fishes.
Sharks track their prey using their _____________________________and large olfactory organs, since their vision is not well developed.
The __________________________________rarely exceed 1 m.
More than half of _______________________________________________, specialized for a bottom-feeding life-style.
Unlike sharks, which swim with thrusts of the tail,
The ______________________________________________________________, in which the vertebral column turns upward and extends into the dorsal lobe of the tail, provides lift and thrust as it sweeps to and fro in the water, and the broad head and flat pectoral fins act as planes to provide head lift.
Sharks are well equipped for their _________________________________.
The tough leathery skin is covered with ________________________________ that are modified anteriorly to form replaceable rows of teeth in both jaws.
Sharks have___________________________________________used to guide them to food.
________________________________________________________________, but a well-developed lateral line system is used for detecting and locating objects and moving animals (predators, prey, and social partners).
It is composed of a
Inside are ___________________________________________________ that are extremely sensitive to vibrations and currents in the water.
The receptors, _______________________________________________, are located on the shark's head.
Rays are distinguished by their __________________________________________ and the much-enlarged pectoral fins that behave as wings in swimming.
The gill openings are on ______________________________, and the ___________________________________________ are unusually large.
The teeth are adapted for crushing the prey –
In the stingrays, __________________________________________have disappeared, and the tail is slender and whiplike.
The stingray tail is armed with one or more _____________________________