Marine Ecology, April 18, 2007

Invertebrates 3: Phylum Arthropoda

Phylum Arthropoda

Major arthropod features Body segementation/specialization of

regions Paired, jointed appendages Exoskeleton

Several non-living layers of cuticle, secreted by the epidermis Contains chitin

Cuticle also forms mouthpart structures, lining of digestive tract, eye lens, and wings.

Phylum ArthropodaSubphylum Crustacea features Two pair of antennae, followed by three pairs

of mouthparts Compound eyes, sometimes on stalks Head and thorax often combined into a

"cephalothorax“ Appendages

Biramous (double-branched) appendages Not apparent in many crustaceans

Often have calcium carbonate in cuticle (“crustose”)

Many have gills. In common crustaceans, attached to base of legs,

extend up into thorax.

Other concepts/terms

Thoracic appendages often are walking legs or modified for food handling

Abdominal appendages sometimes modified as "pleopods", broad swimming appendages.

Very end of abdomen often formed by two types of structures; can see these clearly in shrimp.

Telson Uropods

Order Amphipoda(Beach hopper)

Order Isopoda

Idotea sp.

Ligia pallasii

Order Decapoda

Carapace completely covers head and thorax

Eight pairs of thoracic appendages3 as modified

mouthparts (maxillopeds)

5 pairs as walking legs

Order Decapoda

Pagurus sp.

Petrolisthes cinctipes

Pachychelis rudis*Add me to your list!

Shore crabs

Pachygrapsus crassipes

Hemigrapsus oregonensis

Hemigrapsus nudus

Cancer sp. crabs

C. antennarius C. productus

C. magister C. oregonensis

Pugettia producta: kelp crab

Order Cirripedia: the barnacles

Balanus sp.

Chthamalus sp.

Pollicipes polymerus