Insects, crabs, lobsters, etc…. Phylum: Arthropoda Insects, crabs, lobsters, etc….

General Information Diversity: “Arthropod” – jointed legs (appendages) Over 85% of all known animals are arthropods The most successful animals on the planet! They live in the widest range of habitats and eat the greatest varieties of food “Arthropod” – jointed legs (appendages) Appendages are used for eating, moving, mating, respiring, feeling, sensing, or defense

Group: Crustacea The word crustacean originates from the crusty exoskeleton produced by crustaceans Chitin – the organic material produced by the crustacean to form a hard exoskeleton this distinguishes them from mollusks whose shells are made of calcium carbonate (CaCO3) “Insects of the sea” Live in all aquatic environments plus a few land-dwellers

Anatomy Exoskeleton (outer shell) Cephalothorax Swimmerets Hard, protective outer surface; this shell must be molted in order for the arthropod to grow Muscles attach to the inside of the skeleton Cephalothorax the fused head and thorax section; literally means “head breastplate” (Fig 7-4) Swimmerets the posterior pairs of jointed appendages (legs) that mostly function as swimming legs Walking Legs the middle pairs of legs that are used for most movement Maxillae & Mandibles The anterior appendages that are used for food getting apparatuses Antennae Anterior pairs of appendages that are used as sensory organs

Habitat Most crustaceans live in the ocean Some live in freshwater Lobsters, shrimp, crabs… Some live in freshwater Crayfish & crabs Few live on land Isopods and pill bugs Even fewer are extremophiles! Kiwa hirsuta 

Freshwater Crab Horseshoe Crab Another freshwater crab Kiwa hirsuta or the Yeti Crab

Sexual Reproduction Lobsters & Crayfish …. Sex is determined by (somewhat) easy to see external structures Swimmerets – Males: Large and point towards the front of the body Use the 1st pair to transfer sperm to the female Females: Have hairs on the swimmerets that make them look like feathers Used to hold fertilized eggs against the abdomen until ready to hatch

Sexual Reproduction Crabs They have smaller abdomens with not so easy to see reproductive structures Males: Narrow abdomen that fits into a groove on the underside of the cephalothorax Females: The abdominal flap is very broad and covers most of the underside of the cephalothorax She can store sperm until her eggs are ready The female holds the fertilized eggs between the abdominal flap and the body with a natural adhesive This is sometimes referred to as “berrying” or “berried”