Animal Biology Spring 2010

Search this site

E) Physiology

·         Body form is so varied throughout the crustacean groups that the only feature all crustaceans share is the possession of two pairs of antennae at some stage in their life cycle

·         An exoskeleton made of the protein chitin and calcium

o   This external shell, in addition to being protective, gives rigid support for the attachment of the muscles.

·        The exoskeleton is made of separate plates connected by thin membranes

·         This segmented exoskeleton creates joints, allowing the crustacean to move its body and appendages

·         Crustaceans have two pairs of antennae

·         In crustaceans the head is fused with the thorax forming the cephalothorax. Their body thus is divided into cephalothorax and abdomen.

·        Molting – crustacean grows but its exoskeleton does not – the animal must molt its old exoskeleton in order to accommodate expanding body
·         It is possible to find a group of crustaceans that feeds in just about every way imaginable
RESPIRATION

·         Most crustaceans have a heart perforated by openings, or ostia, which admit venous blood from the pericardial sinus in which it is located

o   The heart may be elongated and tubular and extend through the greater part of the body

o   Generally more compact organ

o   It pumps blood through an arterial system or through connecting sinuses or lacunae within the body tissues

·         Some lower crustacean do not have a heart, and the muscular movements of the animal or its alimentary tract circulate the blood through the body cavities or sinuses

·         The blood of the great majority of the crustaceans is bluish, because it contains the respiratory pigment hemocyanin.

o   A few crustaceans have red blood as a result of the presence of erythrocrurion
DIGESTION

·         The digestive tube of arthropods is complete, containing mouth and anus. Arthropods are protostome animals, i.e., in their embryonic development the blastopore originates the mouth.

·         In crustaceans a pair of excretory organs called green glands exists.
    •     The green glands collect residuals from the blood and other parts of the body. They are connected by ducts to excretory pores located under the base of the antennae and these pores release the excretions outside.

·         In crustaceans, typical aquatic beings, there are richly vascularized gills that make contact with water and permit gas exchange.

 

 http://animaldiversity.ummz.umich.edu/site/resources/biodidac/crus003b.gif/medium.jpg

 http://www.serc.si.edu/education/resources/bluecrab/images/Mo_3_jpg.jpg