Compare and Contrast the Jawless and Jawed Fish

question 53

Essay

Compare and contrast the jawless and jawed fish. How do scientists think the jaw first evolved in fishes? Was the evolution of the jaw related to feeding?

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Definitions:

Merocrine

A type of exocrine secretion where cells secrete substances without losing cytoplasm.

Apocrine Gland

A type of gland found in various parts of the body that secretes substances (often involved in scent and sweat) into hair follicles.

Hyponychium

The area of epidermis beneath the free edge of the nail plate, forming a barrier to protect the nail bed.

Nail Root

The part of the nail located under the skin behind the fingernail or toenail, from which the nail grows.