Tabla de Contenidos
Many animals have their skin covered with hair; In particular, mammals cover their bodies with fur that protects them from moisture and conserves body heat. Whales are mammals but most of the images we see show no evidence of fur on their skin. However, whales can have hair; there are more than eighty species of whale and the hair is only visible in some of them. Adult whales do not usually have hair on their skin, but some did when they developed in the womb, in their fetal stage.
hair on whales
Mysticetes are a group of marine mammals made up of species of whales, dolphins, and porpoises; they are also known as baleen whales since they have baleen instead of teeth, although there is no visible fur. The location of the hair follicles is similar to that of the whiskers in terrestrial mammals. They fan out along the upper and lower jaw line, on the chin, along the midline on top of the head, and sometimes around the nostril. The humpback whale shown in the figure below is part of the baleen whales. Depending on the species, baleen whales can have between 30 and 100 hairs and generally have more hair on the upper jaw than on the lower jaw.
In the baleen whale group the hair follicles are probably more visible in the humpback whale. This mammal has golf ball-sized bumps on its head, called tubercles, that house the hairs. Inside each of these bumps is a hair follicle.
Toothed whales or odontocetes are a different group. Most of these whales lose their hair shortly after birth; in their fetal stage they have some hairs on the sides of their mouths. However, there is one species that has visible hairs in its adult stage: the pink dolphin. Also called the Amazon dolphin or boto ( Inia geoffrensis ), it has stiff hairs on its snout. It is believed that these hairs are associated with the boto’s ability to find food in the muddy bottoms of lakes and rivers.
Usefulness of beards and hairs
Baleen whales have hair-like structures in their mouths called baleen that are made up of keratin, a protein that also makes up hair and nails. The beards play a role in the feeding of the mysticetes. This group of whales has two feeding strategies: filtering or ramming. Right and gray whales are filter feeders; they swim slowly with their mouths open and thus enter water with zooplankton that remains trapped in their baleen. Meanwhile, Antarctic whales that feed on krill , small crustaceans, or those that feed on small fish are lunge feeders, swimming rapidly with their mouths open towards the school, thus catching the organisms that they later ingest.
The role of the external hair is not clear since it is scarce and does not have the function of fur in terrestrial mammals. Since there are many nerve endings in and around hair follicles, they may be used as a detection tool for the whale. Perhaps they use them to detect prey; it has been suggested that prey may rub against hairs and allow the whale to determine when it has encountered a high enough prey density to develop its foraging strategy. Another possibility is that the hairs are used to detect changes in currents or turbulence. It is also thought that the hairs may have a social function: perhaps calves use them to communicate their need to suckle, or perhaps adult whales use them during mating.
Sources
- Goldbogen, JA, Calambokidis, J., Croll, DA, Harvey, JT, Newton, KM, Oleson, EM, Schorr, G., RE Shadwick. Foraging behavior of humpback whales: kinematic and respiratory patterns suggest a high cost for a lunge . J Exp Biol 211, 3712-3719, 2008.
- Mead, JG, JP Gold. Whales and Dolphins in Question . Smithsonian Institution Press, 2002.
- Mercado, E. Tubercles: What Sense Is There? Aquatic Mammals, 2014.
- Reidenberg, JS, JT Laitman. Prenatal Development in Cetaceans. In Perrin, WF, Wursig, B. and JGM Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2002.
- Yochem, PK, BS Stewart. Hair and Fur. In Perrin, WF, Wursig, B. and JGM Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2002.
- WWF. Whales and Dolphins: Two Very Particular Mammals . 2010.
