Question

Crustaceans have better-developed sense organs than do the annelids because they have _______ ________ — delicate projections of cuticle distributed over the body, and especially the mouthparts.

a. Setal bristles
b. Chemoreceptors
c. Antennules
d. Setae

Answer 1

Crustaceans possess setae, which are delicate projections of the cuticle that function as specialized sense organs, allowing them to detect environmental cues more effectively than annelids.

Step-by-step explanation:

Crustaceans have better-developed sense organs than annelids because they have setae — delicate projections of cuticle distributed over the body, and especially the mouthparts. These setae function as mechanoreceptors and chemoreceptors, which are essential for crustaceans to interact effectively with their environment. Different crustacean species exhibit a variety of setae adapted for specific functions, such as food detection, environmental navigation, and predation.

Crustaceans like crayfish have a complex nervous system with a brain formed by the fusion of segmental ganglia and a ventral nerve cord linking additional ganglia. Their sensitivity to the environment is further enhanced by two pairs of antennae, which often bear many tiny setae that sense chemical cues in the water.