describe the segmentation of a crustacean
head = 5 segments (1-5; 2 antennae, 3 mouthparts)
thorax = 8 segments (6-13; pereopods walking legs)
abdomen = 6 segments (14-19; pleopods swimming legs + uropods)
what types of appendages can crustaceans have?
endopod = closer to midline
exopod = farther from midline
stenopodial = leg like appendage, long exopod and endopods
phyllopodial = leaf like appendage, round flat exopod and endopods
what is the name of the larval stage shared by crustaceans?
nauplius
what classes are within the crustacean group?
Malacostraca, Cirripedia, Branchiopoda, Ostracoda, Copepoda, Xenocarida
what characteristics do the maxillopodans (Branchiopoda, Cirripedia, Copepoda) have?
<19 segments, no appendages on abdomen
Branchiopods = repeated phyllopodial appendages
Cirripedia = reduced abdomen
Copepoda = 3 tagmata
what are some unique traits from Ostracoda?
- no abdomen
- 7 segments total (5 head, 2 thorax)
- mineralized carapace covering entirety of body
- pereognaths (last head segment becomes walking legs)
what three orders are within Branchiopoda?
Anostraca (sea monkeys), Cladocera (Daphnia, Podon), Conchostraca
what segmentation does Cladocera have?
- 1 pair of maxillipeds
- 2nd antennae used to swim
- 5-6 thoracic segments
- no abdomen
what segmentation does Anostraca have?
- 2 pairs of maxillipeds
- 6 swimming thoracic segments
- 6 legless abdominal segments
- no carapace
what segmentation does Conchostraca have?
- no maxillipeds
- dozens of segments
- 1st antennae = swimming
- large carapace
what are three orders within Copepoda?
Calanoidea, Cyclopoidea, Harpactacoidea
what orders are within Malacostraca?
“Eucarida” (true shrimps):
- Decapoda
- Euphauseiacea
“Peracarida” (false shrimps)
- Isopoda
- Amphipoda
“Hoplocarida” (armed shrimps)
- Stomatopoda
why is Phyllocarida considered a basal lineage?
- no maxillipeds
- unfused cephalothorax
- 8 thoracopods = phyllopods
- 8 pleopods = stenopods
what are the differences between Eucarida and Peracarida?
Eucarida has:
- carapace fused to thoracic segments
- stalked eyes
- no brood pouch
