12-06-2013, 03:18 PM
CRUSTACEANS
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INTRODUCTION:
It is an arthropoda
The tough body covering, or outer skeleton, is the animal’s exoskeleton.
It is made of chitin, a type of carbohydrate.
The exoskeleton functions not only as a protective cover for arthropods but also as a place of attachment for their muscles.
we refer to the major subdivisions a classes, the most important in marine habitats being the class Crustacea (meaning they have a “crust” or “shell”).
Crustacean Features:
The part of the exoskeleton that covers the head and chest regions is called the carapace.
Crustaceans such as lobsters, crabs, and shrimps have five pairs of legs located under their carapace.
Therefore, they are referred to as the decapods (meaning “ten legs”)
The claws, which are used in food-getting, are the first pair of legs; the four other pairs
are the walking legs.
The head contains two eyes, two pairs of anten-nae, and special mouthparts used for feeding.
The Lobster:
Two common lobster species:
1.Northern lobster (Homarus americanus)
2.Spiny lobster (Panulirus argus).
The Northern Lobster has two large claws, which are absent in the Spiny lobster.
The northern lobster lives in the rocky subtidal zone, from Labrador to Virginia.
The spiny, or rock, lobster is found in the waters of Florida, the Gulf of Mexico, and California. (There is also a European species of spiny lobster.)
Lobsters are aggressive and often fight amongst themselves. If one lobster grabs the claw of another lobster, the latter can escape by releasing its arm from its socket.