Description:
Family Pinnotheridae (pea crabs) is a family of very small crabs that
typically live symbiotically with other species, such as within the
mantle cavity of bivalves, in the tube of polychaete worms or ghost
shrimp, the cloacas of sea cucumbers, or in the atrial chamber of
tunicates. The mouth parts of species in this family do not taper
anteriorly. They have no rostrum nor teeth either between the eyes
or along the lateral margins of their carapace. Pinnotheres taylori
has a carapace less than 1.5x as wide as long. The carapace is
generally soft (though the carapace of this individual seemed fairly
firm). There is no groove running back along the dorsal surface of
the carapace from near each eye, but they do have two small
tubercles just behind the middle of the dorsal carapace. The carapace
of males has fine setae. The dactyls of their walking legs are nearly
straight, and the dactyl of leg 5 is only slightly longer than that of
legs 3 and 4 (not more than 1/5 longer). Carapace width to 8 mm. How to Distinguish
from
Similar Species:
Pinnotheres pugettensis is also often found living inside ascidians (tunicates) but the dactyl of the 5th leg of Pinnotheres pugettensis
is about 1/5 or 1/4 longer than that of legs 3 & 4. They also are
generally in tunicates but favor those that are not transparent.
The dactyls of the walking legs of Fabia subquadrata are definitely curved and there is a longitudinal groove back along the dorsal carapace starting near each eye. F. subquadrata lives symbiotically with bivalves rather than tunicates. Geographical Range:
British Columbia and northern Washington Depth Range:
11-64 m. Habitat:
Within the tunic of transparant tunicates. Biology/Natural
History:
This species is symbiotic within the transparent tunic of ascidians Corella willmeriana, Ascidia paratropa, and Ascidia ceratodes.
References:Dichotomous Keys:
General References:
Scientific Articles:
Web sites:
General Notes and
Observations: Locations,
abundances, unusual behaviors:
The underside of the same female. As with many crab species, the abdomen is much wider than in a male. She may or may not be carrying eggs. Photo by Dave Cowles, July 2025 Authors and Editors
of
Page:
Salish Sea Invertebrates web site provided courtesy of Walla Walla University |