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Unidentified Animal 3
Based on the videos below see if you can identify the specimen that was retrieved in the otter trawl.
For each question there will be 1 - 3 choices for you to decide between. To move to the next option, click "Choice A", "Choice B", or "Choice C". If you answer a question incorrectly, you will be directed to a drawing of an organism. Click the blue button below the drawing to return to the question to try again.
Question 1
Choice A: Largest claw is slender (width less than 1/2 length), almost cylindrical, without saw-teeth on outer edge of claw; carapace length up to 12 mm (1/2").
Choice B: Largest claw is broad (width more than 1/2 length), flat or oval in cross section, with saw-teeth on outer edge; carapace length may exceed 12 mm (1/2").
Question 1
Question 2
Question 2
Choice A: Large claws are nearly hairless and without purple ands (but may have a darkish longitudinal stripe); length of eyestalks are less than 3.5 times the greatest width; prefers shells of mudsnails (Ilyanassa), periwinkles (Littorina) and other small snails; very common.
Choice B: Large claws are hairy and may have 4 or 5 distinct purplish bands; length of eyestalks are more than 3.5 times the greatest width; prefers shells of the greedy dovesnail (Anachis avara) or the bruised nassa (Nassarius vibex); tiny, up to 6 mm (1/4") carapace length; not common.
Question 3
Question 3
Choice A: Moveable finger of major claw with a projecting angle on outer edge; claws are bumpy, without many long spines or an orange stripe; very common; prefers shells of moonsnails (Euspira), whelks (Busycon, Busycotypus) and other large snails.
Choice B: Moveable finger of major claw is curved, not angled, on outer edge; claws have a broad longitudinal red-orange stripe; claws have many small bumps and spines; prefers shells of the waved whelk (Buccinum undatum).
Longwrist
Pagurus longicarpus, longwrist hermit crab
Body is gray or tan, large claw is whitish; up to 11 mm (1/2") carapace length, very common.
major claw is slender, cylindrical and curved
whitish finger tips
Pagurus pollicaris, flatclaw hermit crab
Reddish brown, up to 3 cm (1 1/4") carapace length; very common.
saw-toothed edge
angle on finger
major claw is broad and flat
CORRECT
You have successfully identified the Flatclaw Hermit Crab
Flatclaw
Pagurus acadianus, Acadian hermit crab
Body brown, legs orange or reddish-brown with white bases, claws with longitudinal red-orange stripe and whitish edges; up to 3 cm (1 1/4") carapace length.
no angle on finger
major claw is broad, oval and has red-orange stripe
saw-toothed edge
Acadian
Pagurus annulipes
anterior part of body, dorsal view
carpus of right second pereopod (male, shield length, 1.3mm)
carpus of right second pereopod (male, shield length, 2.5mm)
Pagurus annulipes
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