1. Arthropods

3. Subphylum Crustacea Over 67,000 species Primarily aquatic
Lobsters, crayfishes, shrimp, crabs, water fleas, copepods, barnacles
Primarily aquatic
Mostly marine but some freshwater
Only arthropods with 2 pairs of antennae
Mandible
2 pairs of maxillae

5. Lobsters

6. Crayfish

7. Shrimp

8. Shrimp

9. Crabs

10. Water Fleas

11. Water Fleas

12. Copepods

13. Copepods

14. Barnacles

15. Barnacles

16. Subphylum Crustacea Major tagmata Carapace Head, thorax, abdomen
A hard outer covering or shell made of chitin

17. Subphylum Crustacea Form & Function Appendages
Swimmerets (abdominal appendages)
Endopod & exopod (inner & outer branches)
Attached to one or more basal segments (protopod)

18. Subphylum Crustacea General – Majority are free swimming
Very important components of aquatic ecosystems
Have two pairs of antennae (only arthropods with these)
Most have between 16 and 20 segments
Compound eyes (detects motion)
Crabs & crayfish are on the ends of movable eyestalks

19. Subphylum Crustacea Ecdysis Feeding Habits (ekdysis = strip off)
Periodic shedding of old cuticle for a larger one
Feeding Habits
Suspension feeders
Plankton, detritus, bacteria
Predators
Larvae, worms, crustaceans, snails, fishes
Scavengers
Dead animals & plant matter

20. Subphylum Crustacea Class Branchiopoda
branchia – gills, podos – foot
Four orders are recognized:
Anostraca – fairy shrimp and brine shrimp
Notostraca – tadpole shrimp (Triops)
Conchostraca – clam shrimp (Lynceus)
Cladocera – water fleas (Daphnia)
Have reduced first antennae and second maxillae
Legs are flattened and leaflike (phyllopodia)
chief respiratory organs

21. Subphylum Crustacea Class Maxillopoda
include barnacles, copepods, ostracods, and related groups.
Most are small
Most feed by means of their maxillae
Barnacles are an exception
Barnacles feed with thoracic appendages, but in a way that is unique among crustaceans.
basic plan of 5 head and 10 trunk segments
(6 thoracic and usually 4 abdominal)
The abdominal segments typically lack appendages; appendages elsewhere on the body are usually biramous.

22. Subphylum Crustacea Class Maxillopoda
Subclass Ostracoda
Enclosed in a bivalve carapace (resemble tiny clams; mm long)
Fusion of trunk segments; scavenge food, feed on detritus, or collect particles from water
Subclase Copepoda
Small, elongated, lack carapace and retain simple, median nauplius eye in adults
(kōpē – oar, podos – foot)

23. Ostracoda
Copepoda

24. Subphylum Crustacea Class Maxillopoda
Subclass Branchiura
Branchia – gills, ura – tail
Primarily fish parasites (despite name, has no gills)
Broad, sheildlike carapace, compound eyes, 4 biramous thoracic appendages & short abdomen
Subclass Cirripedia
Cirrus – curl of hair, pedis – foot
Includes barnacles, as well as smaller orders of burrowing or parasitic forms
Barnacles are sessile as adults
Attach to their substrate by stalk (gooseneck barnacles)
Attach directly (acorn barnacles)
Typically, a carapace (mantle) surrounds their body and secretes a shell
Head is reduced, abdomen is absent, and thoracic legs are long, many-jointed cirri with hairlike setae

31. Subphylum Crustacea Class Malacostraca
(malakos – soft, ostrakon – shell)
Largest Crustacae class
Trunk usually has 8 thoracic and 6 abdominal segments
each with a pair of appendages
Many marine &freshwater species
Includes krill, sow bugs, lobsters,
crayfish, shrimp, and crabs

32. Isopoda (Class Malacostraca)
(isos – equal, podos – foot)
Commonly dorsoventrally flattened, lack a carapace, and have sessile compound eyes
Abdominal appendages bear gills
Common land forms are sow bugs (pill bugs)

34. Amphipoda (Class Malacostraca)
(amphis – on both sides, podos – foot)
Resemble isopods in that members have no carapace and have sessile compound eyes
However, they are usually compressed laterally and their gills are in the thoracic position

37. Euphausiacea (Class Malacostraca)
(eu – well, phausi – shining bright, acea – pertaining to)
Group of about 90 species
Important as oceanic plankton known as “krill”
Occur in great oceanic swarms
Eaten by baleen whales and many fish

38. Krill

39. Krill

40. Krill

41. Whale eating Krill

42. Decapoda (Class Malacostraca)
(deka – ten, podos – foot)
five pairs of walking legs
First is often modified to form pincers (chelae)
Lobsters, crayfish, shrimp, and crabs

44. Lobsters

45. Crayfish

46. Crabs