Phylum Arthropodaclass

Crustacea

Largest phylum of animals w/ approxOne million known species

Includes: insects, spiders, crabsBarnacles, shrimp, & lobsters

General characteristics• Bilaterally symmetric• Have jointed appendages (legs &

mouth parts)• Exoskeleton made of chitin and

hardened by CaCO3• Grow by molting

• Molting:• Old exoskeleton is shed leaving

the animal soft• The animal brings in water to

expand itself• A new exoskeleton is secreted

by specialized tissue

• Exoskeleton provides protection, support, & flexibility• Also imposes

limitations to grow & size

Class: Crustacea

• 30,000 species primarily marine• Gill-breathing• 16-20 segments• Open circulatory system• Specialized appendages for food gathering, walking,

fighting, defense, etc.• Start out life as a planktonic larvae• Ex: lobsters, crayfish, shrimp, crabs, copepods,

barnacles, etc.• Giant King Crab = largest crustacean (~12ft)• Heaviest is the lobsters (up to 48 lbs!!)

• Have two pairs of antennae (one pair smaller than the other)• Small, planktonic crustaceans

include copepods,

• barnacles, isopods, krill

Barnacles

• Chitin exoskeleton & secretes CaCO3 shell.

• Feathery feet for filter feeding plankton• Some attach to docks or boats and a few on

whales• Must close up with an operculum during low

tide to avoid desiccation (drying up).

Barnacles and Crabs • http://www.youtube.com/watch?v=VKhY-gLGPCk&safety_mode=true&persis

t_safety_mode=1&safe=active

• Barnacle info• http://www.youtube.com/watch?v=49Aev-HA9R4&safety_mode=true&persis

t_safety_mode=1&safe=active

• Giant Crabs• http://www.youtube.com/watch?v=aPJ74X_J_-4&safety_mode=true&persist_

safety_mode=1&safe=active

• Horseshoe Crabs• http://www.youtube.com/watch?v=e8KlAmtIu1E&safety_mode=true&persist

_safety_mode=1&safe=active

• Molting horseshoe crab• http://www.youtube.com/watch?v=Daz8nkh-pWM&safety_mode=true&persi

st_safety_mode=1&safe=active

• Other larger crustaceans include shrimp, lobsters & crabs• Considered decapods (5 pairs of

legs)• Body consists of cephalothorax

(fused head & thorax) & abdomen

• Crabs have a compact abdomen & a broad cephalothorax• Abdomen usually

tucked under

Male

Female

Abdomen with eggs

Lobsters• http://www.youtube.com/watch?

feature=endscreen&v=d5uQ317Osxw&NR=1&safety_mode=true&persist_safety_mode=1&safe=active

• Slipper lobster• http://www.youtube.com/watch?

v=8gBtsboSkOU&safety_mode=true&persist_safety_mode=1&safe=active

• Spiny Lobster• http://www.youtube.com/watch?

v=o2QDJwOIa7s&safety_mode=true&persist_safety_mode=1&safe=active

• Lobster Life Cycle: Safari Montage

Giant Spider Crab

King and Coconut Crabs