1. Intertidal organisms 3: Phylum Arthropoda
Marine Ecology, April 25, 2007
Intertidal organisms 3:
Phylum Arthropoda

2. 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 mouthparts, lining of digestive tract, eye lens, and wings.

3. Phylum Arthropoda Subphylum Crustacea features
Two pairs of antennae; 3 pairs of mouthparts
Compound eyes, sometimes on stalks
Body regions:
Head and thorax often  "cephalothorax“
Abdomen
Thoracic appendages (always)
Abdominal appendages (in some)
Often have calcium carbonate in cuticle
Many have gills
Often attached to base of legs, extend into thorax.

4. Other concepts/terms
Thoracic appendages: walking legs and/or food handling
Abdominal appendages sometimes modified as "pleopods", broad swimming appendages.
Very end of abdomen in many:
Telson
Uropods

5. Reproduction Mating varies: Brooding of eggs/young
Males provide females with spermatophores
Sperm storage occurs in some.
Brooding of eggs/young
Some with direct development
Many with pelagic larvae
female releases fertilized eggs or
Females release larval forms

7. Order Amphipoda (Beachhopper)

8. Order Isopoda
Idotea sp.
Ligiapallasii

9. Order Decapoda Carapace covers head and thorax
Eight pairs of thoracic appendages
3 pairs assist with food handling (maxillopeds)
In addition to the three pairs of mouthparts
5 pairs as walking legs (includes chelipeds)

10. Order Decapoda Petrolisthes spp. Pagurus sp. Pachychelis rudis
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11. Shore crabs Hemigrapsus nudus Pachygrapsus crassipes
Hemigrapsus oregonensis

12. Cancer sp. crabs C. antennarius C. productus C. magister
C. oregonensis

13. Reproduction: Cancer spp.

14. Reproduction

15. Pugettia producta: shield-backed kelp crab

16. Order Cirripedia “Test”: barnacle’s calcareous plates
Moveable valves allow opening, closing
Test is in addition to exoskeleton
Filter-feeds with thoracic appendages
No abdomen
Reduced head

18. Order Cirripedia: the barnacles
Balanus, Semibalanus sp.
Pollicipes polymerus
Chthamalus sp.

19. Cirripedia: life cycle