Crustaceans Advanced Life Science Rainier High School Mr. Taylor

Crustaceans Include crayfish, lobsters, crabs, sowbugs, and barnacles. Have chewing jaws (mandibles) Major food source for people and marine food chains – “Insects of the sea”

Crustaceans Larval form called a naplius. – 3 pairs of appendages – Molts several times before adulthood Respiration (in adults) – Exchange oxygen and carbon dioxide in gills

Crustaceans Decapods – Includes crayfish, lobsters, shrimp, crabs – Have 5 pairs of legs Anterior pair called chelipeds and used mostly for gathering food and defense 4 pair of walking legs

Crustaceans Decapods – 2 body sections Head and thorax fused into cephalothorax that is covered by a carapace made of chitin Abdomen – Has appendages called swimmerets that are used in swimming and reproduction – Tail is called a uropod and is used for propulsion – Some have a ridge along the top of the abdomen called a telson

Crustaceans Decapods – Digestion Will eat almost anything organic Food taken in and ground up in the stomach, passes through intestine, passes undigested nutrients out anus – Excretion Some eliminate nitrogen wastes through “green glands”, some diffuse across gills.

Crustaceans Decapods – Nervous System Have brains with nerves to antennae and antennules Ventral nerve cords with ganglia at each segment 2 compound eyes with >2500 lenses each – Reproduction Sexual reproduction, external fertilization

Crustaceans Barnacles – Sessile as adults, free-swimming naplius – Naplius will attach to almost anything stationary or solid Secrete scales to attach and protect Extend feathery legs through topmost closeable scales to sift food from surrounding water. Are hermaphrodites but rarely fertilize their own eggs.

Crustaceans Isopods – Pillbugs and sowbugs – Only true terrestrial crustaceans Modern species look very much like fossilized isopods.

Crustaceans … Decapods

Crustaceans … Barnacles

Crustaceans … Isopods