Question

Compare your crayfish with one of the opposite gender.

What body region or segment are the walking legs attached to? What about the swimmerets?

How does the shape of each appendage type fit its particular function?

1. Chelipeds:
2. Walking legs:
3. Swimmerets:

Answer 1

Crayfish is otherwise called crawfish, crawdad, or freshwater lobster. They are invertebrates which reside in freshwater and are commonly found in streams, ponds, lakes, and swamps. The body of crayfish is divided into two parts: the cephalothorax and abdomen. Attached to the thorax, crayfish have four pairs of walking legs and one pair of chelipeds. In addition to this, they also have limbs present under the tail known as swimmerets.

Male and female crayfishes, even though look similar, have several important morphological differences. Some of the features that distinguish males from females are as follows:

· Males are generally larger in size than females.

· Males have large chelae and narrower abdomens.

· Males have an extra set of enlarged and hardened swimmerets.

· A small hole is present behind the swimmerets in females. This hole is absent in males.

· The abdomens of females are broader in order to carry her brood.

Walking legs of crayfish are called pereipods. These are attached to the thorax. These structures are not only used for locomotion but also for probing cracks and crevices on rocks to obtain food. Moreover, crayfish tend to lose walking legs while attacked by predators, but are also able to regenerate them eventually.

Swimmerets are small limbs attached to the underside of the abdomen beneath the tail. They are used for swimming and move water over the gills. Males have an extra set of harder enlarged swimmerets. This is used for grasping females and depositing sperms into females during copulation.

1. Chelipeds of crayfish are large clawed structures that are attached to the front of the thorax. These are used for capturing prey, cutting food, attacking, and defending against predators.

2. Walking legs or pereiopods are attached to the thorax. They are small appendages whose uniform motion enables the organism to walk, gather food, and move water over the gills.

3. Swimmerets are small appendages attached to the abdomen. The enlarged hardened swimmerets in males enable it to grasp the female during copulation.