Taxonomy of Shellfish

Unit 2 - Sub-phylum Crustacea

2.2.8.2.2. Super-order 2. Peracarida

• Carapace, when present, leaving last 4 thoracic segments uncovered.
  
• Female has a thoracic brood pouch or marsupium.

In this super order consist five orders

Order 1.Mysidacea (Opossum shrimps)

• Mostly marine, some freshwater.
• Body elongated, carapace covering most of thorax.
• Anterior 2 pairs of thoracic appendages form maxillipedes
• Uropods form tail-fan.

Eg. Mysis, Gnathophausia


Order 2.Cumacea

• Small, marine, deep littoral.
• Head and thorax greatly enlarged.
• Abdomen slender with styliform uropods.
• Carapace fused to first 3 or 4 thoracic segments.

Eg. Diastyles, Cumopsis, Leptocuma

Order 3.Tanaidacea

• Minute, marine, up to 4,000 meters in mud or tubes.
• Carapace small and fused to first 2 thoracic segments.
• Telson fuses with last abdominal segment
• Uropods slender.

Eg. Tanais, Apseudes

Order 4.Isopoda (Pill bugs, Wood lice)

• Mostly marine, some freshwater and terrestrial.
• Body dorsoventrally flattened.
• Carapace absent.
• Gills and heart abdominal

Eg. Oniscus, Ligia, Bopyrus, Cryptoniscus

Order 5. Amphipoda (Sand hoppers)

• Mostly marine, some freshwater and terrestrial.
• Body elongated often laterally compressed.
• Carapace absent.
• Gills and heart thoracic.

Eg. Gammarus, Coprelle, Cyamus