Tuesday, July 31, 2007

Whale lice fact sheet

Whale lice (cyamidae) are small crustaceans, not lice despite their name. The name "whale lice" comes from the whalers, as they often had lice (Pediculus sp.) themselves and they saw how there were lots of animals crawling all over the whales as on themselves. Whale lice are between 5-15 mm long and are grouped into 7 genera and 32 species. Many species are physically almost identical and for many years they were classified as one species. Many new discoveries are made all the time, the most recent was 1991. A lice species that used to be classified as Isocyamus deplhinii is now Isocyamus kogiae as they live on pygmy sperm whales (Kogia breviceps).


Classification
Domain           Eukaryota      
Kingdom         Animalia        
Phylum           Arthropoda    
Subphylum     Crustacea       
Class               Malacostraca       
Order              Amphipoda    
Suborder         Corophiidea
Infraorder       Caprellida
Family            Cyamidae      
Genera            Cyamus, Isocyamus,
  Neocyamus, Platycyamus,
  Scutocyamus, Sirenocyamus and Syncyamus


Hosts
The hosts that carry whale lice are both baleen whales (mysticeti) such as right whales, grey whales and rorquals, and toothed whales (odontoceti) such sperm whales, beaked whales, dolphins, and porpoises.

Northern right whales, Eubalaena glacialis and Eubalaena japonica, always have the lice on the same spots: on the rostrum (bonnet), the chin (beard) and above the eyes (eyebrows). Sourthern right whales (Eubalaena australis) also have an edge around the lip which the Northern right whales are missing. The lice have small hooks to cling on to the whales' callosities, which are crusty growths made of the whale itself, barnacles and Caprellids amphipods. On the callosities there are about 5000 Cyamus ovalis which gives them the white color. Between the callosities there are about 200 lice of the species C. glacilis and adult animals have are bout 2000 lice (C. Erraticus) around the genetalia. One whale can have as many as 7,500 lice living on its skin. Cyamus ovalis, C. glacilis and C. erraticus are not three species but 9 species as the right whales (Atlantic right whale, pacific right whale and Southern right whale) have their own unique lice seperated into different species.

Whale lice feed on dead skin cells and dead skin of their host, and other things that get stuck on the whale such as algae, but they do not feed on the whale itself. It is not a real louse nor a parasite, more just a free-rider that cleans the whale. Some whale lice are filter-feeders and eat plankton that drift by the whale.

The whale lice reproduce on the whale. Most are amphipods that have free-swimming stage, but this is something whale lice are missing and the female keep her offsprings in a marsupium on her underside and the offsprings, when ready, crawl onto the whale. Whale lice move from one whale to the other via close contact between mother and calf, or male and female during mating. A newborn calf doesn’t have lice, they are transmitted from the mother. Otherwise the lice stays on the whale throughout its life.

Mutualism or parasitism? When it comes to the interaction between cyamidae and Northern right whales can be classified as somewhere in between mutualism and parasitism. The whale doesn’t really benefit from the lice but the lice gets great benefits and is building its entire life around the whale, it is dependent on the whales lifecycle for its survival. The whale get one way of help as it gets rid of dead skin and other parasites.

For the whale research, the lice is very informative. The lice has been sitting on the whales for miljons of years and followed the evolution of the whales. Research on the lice has given us many answers when it comes to the evolution; for 5-6 miljon years ago the right whale was divided into three species, Southern right whale, Atlantic right whale and Pacific right whale. One, of just a few, Southern right whales crossed the ekvator  for about 1-2 miljon years ago and spread their lice (C. ovalis) to the Pacific right whale. Researchers has found that the lice on the Pacific right whale is closer related to the Southern then the Atlantic. The Southern right whales that crossed the ekvator probably didn’t mate with the Pacific right whale as the C. erraticus, that lives around the genitalia is not affected. This is amazing though right whales can’t cross the ekvator because it is too warm, as they have to much blobber. Whale lice also help researchers to identify individual whales, and makes the research easier. All right whales are unique, but sometimes it is diffecult to tell some individuals apart though they don’t have nay whites pots and are completly black. Witht he help of the lice the whale turns unique in shape and color. Probably the lice is irritating the skin, but it helps the research, which can be seen as a benefit for the whales in the long run.

One reason whales are jumping is to get rid of parasites and lice. Pec-fin slapping and lobtailing can also be a way to get rid of lice. Many species of cetaceans also rubb their bodies against rocks and seabottom, even in captivity. Cetaceans can also get help from birds to get rid of parasites when they come to the surface to breathe.

When we come to the situation for the lice we see that they are in danger in the future, because many of the whales they are living on are endangered. Atlantic and Pacific right whales are endangerd, and the Southern right whale are at risk and in need of conservation. Grey whale populations are at risk, and one population became extinct in the 1700s. Other threatened species of baleen whales are blue whale, fin whale, sei whale, humpback whale, all four species of minke whale, pymgy right whale and bowhead whale. Other whale species at risk are the vaquita, indus river dolphin, irrawaddy dolphin, and different populations of dolphins in certain areas (such as orca, bottlenose dolphin, spinner dolphin, pantropical spotted dolphin, pilot whales and melonheaded whale), many beaked whales, sperm whale and kogids.
An action for conservation of cetaceans and keep healthy populations is very important for the whale lice survival. Even if one whale can carry 5000 lice, the less whales they have the more they are at risk for inbreeding. When there are no more whales, there are no more whale lice.

Some of the cyamidae is strictly living on one whale species, such as Cyamus catodontis that only lives on male sperm whales, and Neocyamus physeteris that only lives on sperm whale female and calves. But a few species are finding new hosts, and the Isocyamus deplhinii doesn’t only exist on the shortbeaked common dolphin, it has been discovered on 12 other toothed whales, such as Risso’s dolphins, shortfinned pilot whales and longfinnes pilot whales, whitebeaked dolphin, false orca, bottlenose dolphin, harbour porpoises, rough-toothed dolphin, Gervais beaked whale and orca. But, whale lice is not moving onto other species then cetaceans.

Worms can be seen on most cetaceans, and in the Azores we see these worms hanging from the fins of all dolphin species, and the baleen whales. On the minke whale we can see species as Pennella and Cocconeis ceticolaThe orcas seems to have a Xenobalanus sp.

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