Crabs, Shrimp and other Arthropods

Chapter 10.2-10.4

Crabs

• Crabs are one of the most widely spread animals living EVERYWHERE – they live on land, in freshwater and in the sea from shore areas, to surface waters, to the great ocean depths.

Diagram of the Crab

Crab Diversity• Fiddler crab – digs tunnels in the

sand along shores of bays and inlets.

• Mole crab – lives in the turbulent surf zone along sandy beaches

• Hermit crab – has a soft abdomen and must find empty snail shells to live in

• Spider crab – can grow to 13 feet from leg tip to leg tip and lives at ocean depths

Crab Life Functions

• Much of what the crab does is identical to the lobster.

• Differences include that crabs’ abdomens are folded between their legs and they have no tail.

Crab SexPregnant or “Spongy” Crab

Blue Porcelain Crab

Coconut Crab

Fiddler Crab

Giant Spider Crab

Hermit Crab

King Crab

Mole Crab

Snow Crab “Opelio”

Tasmanian Giant Crab

Other Crustaceans• Shrimp are basically small versions of a

lobster.– Pink Gulf shrimp, shore shrimp,

cleaning shrimp, mantis shrimp• Copepods and krill are almost microscopic

and make up much of the zooplankton• Amphipods and isopods live near the

oceans’ edges sometimes on a substrate• Barnacles are sessile and live in the

intertidal zone

Barnacles must continually be removed

Horseshoe Crabs

• Not a true crab – Class Merostomata

• More closely related to spiders and scorpions

• Has many eyes

• Mates in estuaries like the Delaware Bay and timing is determined by moon.

• Has book gills and a telson

• Eggs are a vital source of migratory shore bird food.

Horseshoe Crab

Horseshoe Crab

Mating

More Mating

“Green Eggs and Sand”

Baby Horseshoe Crab

Marine Insects

• Pretty much biting insects that live near land–mosquitoes, biting flies

(green head and horse fly), sand-fly (“no see-um”)

–May transmit disease• Not found in high salinity

areas or open ocean

Marine Insects