Ampithoe dalli Shoemaker, 1938
Common name(s): Speckled beach hopper
|A male Ampithoe dalli, 1.7 cm long, found on eelgrass in Padilla Bay|
|(Photo by: Dave Cowles, July 2014)|
Description: As is characteristic of Family Ampithoidae, this gammarid amphipod has a biramous 3rd uropod, both rami of which are shorter than the peduncle (photo). The outer ramus of uropod 3 has two curved teeth at the apex, while the inner ramus has setae plus spines (photo). The outer lobe of the animal's lower lip has a deep cleft. This species has no accessory flagellum on its antennules. Antenna 2 is longer than antenna 1 and is not thickly covered with setae. The palm of gnathopod 1 is definitely oblique and the gnathopod is subchelate (photo). The second gnathopod (photo) is larger than the first, and its sixth article (palm) is ovate and oblique. The second article of pereopods 3 and 4 are rectangular and less than 1/2 as wide as their coxal plates (photo). The posteroventral corner of the second and third epimera are not toothed (photo). The antennae and uropods have just a few short setae. Uropods 1 and 2 do not have a distal tooth on the peduncle. Greenish or brownish with darker speckles. Males to 1.8 cm, females to 2 cm.
Note: Although this individual is male,
the 2nd gnathopod has only a shallow concave spot instead of being
broadly concave as is expected of this species, so the identification
is only tentative.
How to Distinguish from
A. sectimanus is similar but has many long setae on its antennae and uropods, plus gnathopod 2 has only a narrow excavation.
Alaska to California
Intertidal and shallow subtidal;
Algae and eelgrass
This species can survive in less than full seawater salinity (eg in
outer estuaries). Females may be carrying eggs during March to
|Main Page||Alphabetic Index||Systematic Index||Glossary|
Kozloff, 1987, 1996
O'Clair and O'Clair, 1998
General Notes and
abundances, unusual behaviors:
This closer view shows the strong green color with the darker spots.
This view of gnathopod 1 shows that it is subchelate and has an oblique palm.
Gnathopod 2 also has an angled palm and is subchelate. It is larger than gnathopod 1.
The coxal plates for pereopods 3 and 4 are much wider than the second articles of those pereopods, which are rectangular.
3 (on the right) is biramous. The outer ramus (in sharpest focus
here) has two curved distal teeth. The inner ramus (behind it,
less sharp focus) has both teeth and setae. Neither of the two
rami is as long as the peduncle (basal article) of the uropod.
Authors and Editors of
Dave Cowles (2014): Created original page
CSS coding for page developed by Jonathan Cowles (2007)
Salish Sea Invertebrates web site provided courtesy of Walla Walla University