Fishes Continued

Question 1

Characteristics - Fishes

Answer 1

The familiar vertebrae senses of vision, hearing, touch, taste, and smell are used by all fishes to gather information about the environment.

Fishes from all these groups typically breathe using gills to extract oxygen from the water, swim using fins, are covered with protective scales or bony plates, and are cold-blooded.

However, there are also lungfishes that breathe air, fishes with no scales, and sharks, such as salmon shark, that can control their body temp.

Most fishes have a system of sensory organs called the lateral line running along both sides of the body, which detects vibrations made by other fishes and animals moving through the water.

Fins are also a characteristic of most, but not all, fishes. These usually consist of of 2 sets of paired fins (pectoral and pelvic), 1,2, or early 3 dorsal fins, an anal fin, and a caudal (tail fin). The fins are used for propulsion, maneuverability, and stability. Some used their fins to walk along the seabed or like wings to glide above water.

Question 2

Classes Myxini, Petromyzontia (Jawless fishes)

Answer 2

Hagfishes and Lampreys are long, slimy, eel-like fishes with no biting jaws. They do not have a true backbone; instead, a simple flexible rod called a notochord runs the length of the body

Lamprey have a round sucker mouth surrounded by horny, rasping teeth and are mostly parasitic on other fishes.

Hagfishes have a slit like mouth surrounded by 4 pairs of tentacles and are mostly scavengers.

Question 3

Class: Chondrichthyes (Cartilaginous Fishes)

Answer 3

Comprise of sharks, rays, and deep-water chimaeras.

These fishes have an internal skeleton made principally of flexible cartilage. Males have a copulatory organ called a clasper and females hive birth to live young or lay large eggs capsules. Special sense organs, called ampullae of Lorenzini, allow cartilaginous fish to track other animals by detecting their electrical fields.

Sharks have strong, replaceable teeth and rough skiing covered in tiny, toothlike dermal denticles.

Skates and rays are flat with winglike pectoral fins and a long, thin tail.

The chimaeras are scaleless with a large head and rat like tail.

Question 4

Class: Osteuchthyes (Bony Fishes)

Answer 4

All bony fishes have an internal skeleton of hard, calcified bone, though in some primitive species this may be part cartilage. With the exception of the lobe-finned fishes, the skeleton extends into the fins as flexible, moveable rays and spines.
This system allows the fish to maneuver with far greater precision than sharks and rays.

Most bony fishes also have a gas-filled swim bladder, which is used to adjust their buoyancy and is covered in overlapping flexible scales.

Bony fishes have evolved many different and sometimes bizarre body shapes and fin functions that enable them to survive in almost every aquatic habitat.