Anthropods
Hebelen Repreza PAP Bio. p.6 Ms.Guzman
Anthropoda
All the animals in a specific phylum have many similar traits. An examination of represantative animals of phylum Anthropoda would reveal certain similar traits. A list for all these traits would form the basis for deciding if other animals should or should not be classified as anthropods. Within a phylum, however, are a number of small groups called classes. Certain differences among members of anthropoda can be used to group this large phylum into different classes.
Objective
We will focus on two specific classes of anthropods: crayfish and grasshopper, look for similarities and differences in the two, and see their external and internal structures.
Crayfish
Crayfish are readily identifiable by the large set of pincers that stretch out in front to help them find and eat food. Crayfish have a further four sets of legs on which they walk. The hard back shell is called a carapace. This provides protection from predators. Crayfish also have a long muscular abdomen with several protective plates that allow both for movement and further protection. When crayfish are growing they must shed this old hard outer shell, called an exoskeleton. A crack appears between the carapace and the abdomen to allow the crayfish to wriggle free from its old exoskeleton. Crayfish are omnivorous, eating anything from vegetable matter to other sea creatures like small shrimp or larvae.They have appendages in abdomen, their excretory organ is called green gland, respiratory organ:gills, and they have 4 pairs of legs.
Grasshopper
Grasshoppers have a body divided into three parts: head; thorax; and abdomen. Three pairs of legs grow from the thorax. Grasshoppers possess a sturdier set of front wings that protect the rear wings from accidental damage. Grasshoppers are herbivores that often eat vegetation indiscriminately.They do not have appendages, their excretory organ is called malpighian tubules, respiratory organ:spiracles/tubules/trachae, and they have 3 pairs of legs.
What they have in common
Location of nerve cord- ventral, type of circulatory system- open, both have exoskeleton, Legs are jointed,have antennae, and their abdomens are segmented.
Extra information: respiratory system
In the grasshopper, respiration is performed using tracheae, air-filled tubes, which open at the surfaces of the thorax and abdomen through pairs of spiracles. A crayfish breathes by using gills located outside the body underneath the carapace (shell in front of the tail or abdomen).