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Scientific NameCommon NameSummary
Cyamus boopisHumpback whale liceThis is the normal sea-louse species on Humpback Whale (Megaptera novaeangliae). Cyamus erraticus is also mentioned as occuring on this species, per Gruner 1975. However, this is questioned in the 2007 edition of the Light and Smith manual.
Cyamus cetiGray and Bowhead Whale AmphipodThis ectoparasitic amphipod is found on Gray Whale (Eschrichtius robustus) in our area, and on bowhead whales further north. It differs from the very similar Little Gray Whale lice (Cyamus kessleri) by the presence of a greater number of "horns" on the ventral side of the rear segments.
Cyamus kessleriLittle Gray Whale liceThis whale louse is very similar to another gray whale louse - Gray whale lice (Cyamus scammoni), except that it is slightly smaller, broader, and has gills that stick out from the sides of the animal and look like legs, rather than coiled up against the ventral side of the thorax.

The other look-alike whale lice on gray whales is Gray and Bowhead Whale Amphipod (Cyamus ceti), which is similar but has many more little spikes on the ventral side of the thorax segments. C. ceti also has diramous gills, whereas those of C. kessleri are uniramous (not branched).

It is very easy to think that the hind legs of this animal are its antennae, and that its front end is its rear end.
Cyamus scammoniGray whale liceThis is the most common species of whale lice on the Gray Whale (Eschrichtius robustus). It is distinguished from Gray and Bowhead Whale Amphipod (Cyamus ceti) and Little Gray Whale lice (Cyamus kessleri) by its branched gills which look like tiny looped noodles attached to the ventral side. Also, C. kessleri is more likely to be found near the anal and vaginal slits when living on gray whales, and less likely to be found on the head of flippers areas. Look closely: people tend to think that this animal's rear end is in fact its head.