Of Lice and Whales

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By guest blogger and Zoology Department research associate, Ken van der Laan

 

Lousy whales?

Whales, the very large mammals in the sea, have lice crawling over them. They tend to show up as part of white patches on whale skin. Those patches are also made up of white barnacles and callosities. Callosities are raised horny parts of the whale epidermis. The barnacles are actually crustaceans, growing in large colonies. The whale lice, which are also crustaceans, hang on to the whales among the barnacles. Some lice are orange as well as being white. Crustaceans include shrimp, lobsters, crabs, crawfish, beach hoppers, and even the “roly-poly” bugs that live in the leaf litter around the Museum and your house.

 

Whale -biofoulingWhale breach with barnacles on the skin. Top right: Barnacles on the front fin. Bottom right: Lice on the whale body.


Are the whale lice really true lice? No, but there are some external similarities to the lice that are found on birds, on humans, and on other mammals. These lice are pretty small. Human lice are 1 to 6 mm long (0.04 to 0.24 in), about the size of a flea. These lice have six jointed legs. Whale lice are 5 to 25 mm long (0.2 to 1 in) about the size of a bumble bee. Whale lice also have jointed legs, ten in number.

The lice that are on humans, terrestrial mammals, and birds, are actually insects, even though some of the human lice are confusingly called “crabs.” The whale lice, on the other hand, are a kind of shrimp, caprellid amphipods. These “lice” belong to the family Cyamidae, “ghost shrimps.” 


There are different species of cyamids on different parts of the same whale, on the different genders, on different species of whales, and on different populations of whales. The evolution and relationships of whales, the hosts, have been determined by analyzing these distributions of their fellow travelers.

The insect lice crawling around on humans and other land dwelling mammals and birds, in fact, can vector many diseases, including trench foot in World War I, and are mostly considered parasites and are sometimes very harmful. Some, such as chewing lice, just eat dead skin.

Whale -liceWhale louse (Cyamus sp.) from Humpback Whale beached on Stradbroke Island, QLD, Australia 

Are whale lice “parasitic” or even harmful? That depends upon what source you consult. The whale lice eat whale flesh from open wounds and gashes. Most researchers, however, call this “wound cleaning,” as the lice eat dead and decaying tissues; thus benefiting the whales. These lice also eat algae that grow upon the cetacean’s skin. Whales often scrape their bodies on the sea bottom. It’s thought this is to remove barnacles and lice. The lice, however, might actually be a benefit to cetaceans. Various species of fish also swim along with whales and help themselves to a nice helping of protein by consuming the whale lice. This complicates things further. Are the fish a benefit to the whales by limiting potential parasites? Or are they a harm by reducing the number of wound cleaners and algae eaters?

Lousy whales overall?

For much more information on whale lice, read posts from Eric Heupel, writing in 2008 from the Duke Marine Lab:
http://other95.blogspot.com/2008/09/right-whale-lice.html


For more information on determining whale evolution from whale lice genetics check:
http://news.nationalgeographic.com/news/2005/09/0928_050928_whale_lice_2.html

 

 

Both Photos: Shona Marks @ Queensland Museum,
PO Box 3300, South Brisbane Q 4101, Australia
Images are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Australia Licence.

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