Excirolana kincaidi (Hatch, 1947)
Common name(s): Sand beach isopod, Sandy beach isopod
|Excirolana kincaidi, 8 mm long, from Shi Shi beach sand|
|(Photo by: Dave Cowles, Sept 2007)|
How to Distinguish from Similar Species: Excirolana vancouverensis has a rounded tip on its angular telson. Excirolana linguifrons has a broadly rounded or truncate tip to the telson and reaches only 4 mm in length.
Geographical Range: British Columbia to Half Moon Bay, CA
Depth Range: Intertidal
Habitat: Sandy beaches.
Biology/Natural History: These isopods alternately bury themselves in the sand and actively forage for dead animal matter. They seem to be especially active in the shallow swash of retreating waves on sandy beaches. Large numbers may quickly congregate around an animal carcass that washes in on a sandy beach while it is still in the water, and quickly strip the carcass of flesh. This is the most common Excirolana species along the Washington coast. Predators include sanderlings.
Note: Very few crustaceans will actually bite you but this nasty
little creature is definitely one of them. Barefoot waders in an
area with Excirolana will
find that the animals quickly swim toward and swarm over bare feet, biting
them so hard that blood will be flowing within moments. Since the
animals are so small the bites are tiny but painful like a pin prick, and
the animals are often present in swarms of thousands. Rapidly shuffling
the feet reduces but does not eliminate the number of bites.
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Morris et al., 1980
General Notes and Observations: Locations,
abundances, unusual behaviors:
I have seen (and felt!) this species on sandy beaches of the outer coast,
such as Kalaloch beaches, 2nd and 3rd beach, and Shi Shi beach.
This ventral view shows that both sets of antennae are well developed. Some of the pereopods have small hooks on the end. The mandibles are dark and hardened--the better to bite you with!
This closeup ventral view of the head shows the hardened, biting jaws
(mandibles) and the first several pereopods. The maxillae and the
maxillipeds are light colored and lie between the mandibles and the first
pereopods, which have small dark hooklike dactyls. The first pereopod
is has a simple dactyl and is neither chelate nor subchelate. Notice
that the eyes are lateral and can easily be seen from the ventral side.
The spatulate rostrum can be seen protruding between the antennae.
This dorsal view of the telson shows the angular but rounded tip and the long plumose setae on the end. The outlines of the uropods, which are ventral and lateral to the telson, can be seen through the telson.
Notice that both rami of the uropods have flattened plates. Some of the terminal setae from the uropods are projecting beyond the telson.
This ventral view of the telson shows the uropods, which are folded in under the telson in this view but can extend out to the sides to form a tailfan.