Crustacea
Shrimps
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Other than that relating to fisheries, little "basic" research seems to have been done on west-coast shrimps and prawns. Thus, most attention in this section of the ODYSSEY will be on burrow-inhabiting forms (mud and ghost shrimps). These forms are no more closely related to shrimps than they are to many other decapod crustaceans but, for convenience, will be included in this section. There are three main species of thalassinids (mud and ghost shrimps) and about 20 species of shrimps and prawns on the Pacific coast of North America, about one-quarter of which are commercially important.

NOTE so named because of their pale whitish-yellow or pale pink colour

NOTE if you are wondering about the difference between “shrimp” and “prawn”, perhaps the following will help (or not...): 1) the older of the two names, schrympe or shrimpe (likely from the German “schrimpen” meaning to “shrink up”), has been in recorded use from the 14th C., while the word “prawn” has had a more recent origin , 2) shrimps are mostly swimmers while prawns are mostly walkers and, 3) shrimps are generally smaller and prawns larger.  The last is made clear in an entry from the Daily Telegraph newspaper in London in 1865 which states: “Our shrimps have most prawny proportions”.  If you are still puzzled, you can join other authors who get around the problem by referring to them all as shrimps.  In the ODYSSEY, they will be referred to generally by the common name used by the author of the particular research study being considered

   

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Fig. 1.  Eyestalk morphology provides a handy means to distinguish the species Neotrypaea californiensis and N. gigas

Shrimps and prawns along with isopods, crabs, barnacles, and amphipods (in order of appearance in the ODYSSEY) are classified in Subphylum Crustacea of Phylum Arthropoda:

Phylum Arthpropods (lit. “soft” or “shellfish” L.)

Subphylum Crustacea (lit. “crust or rind” L.), referring to the hard calcified exoskeleton

Class Malacostraca includes all the “advanced” crustaceans

Order Decapoda (lit. “ten feet” G.), referring to the presence of 10 legs that characterises the Order (includes crabs, shrimps, lobsters)

Suborder Pleocyemata

Infraorder Thalassinidea (lit. “sea” G.)

Family Upogebiidae, including mud shrimps Upogebia pugettensis

Family Callianassidae, including ghost shrimps Neotrypaea, including N. californiensis, N. gigas, and N. biffari

Infraorder Caridea (lit. “shrimp” L.), including shrimps and prawns

Family Pandalida, including coonstripe shrimps Pandalus danae, spot prawns P. platyceros

Family Hyppolytidae, including broken-back shrimps Spirontocaris spp., Heptacarpus sitchensis, H. brevirostris

Family Sergestidae, including Eusergestes similus, a midwater-inhabiting vertical-migratingspecies

Family Crangonidae, including Crangon franciscorum, C. nigricauda

Family Thoridae, including the purported cleaner shrimp Lebbeus mundus

NOTE formerly “Callianassa”, three species of which co-occur along the west coast from Alaska to Baja California: Neotrypaea californiensis, N. gigas, and N. biffari. The last may be synonymous with N. affinis, a small ghost shrimp found in the southern California/northern Baja region that co-inhabits burrows with a blind goby Typhlogobius californiensis. Researchers in California are able to separate the first two species using genetic (allozyme) markers, but also provide a handy morphological distinguishing feature: length and shape of the distal outer edges of the eyestalks (Fig. 1).

Pernet et al.   2010   J Crust Biol 30: 323