Pilomatricoma: A New Species?
The term “pilot whale” was first used in 1877 by American naturalist John James Audubon. It refers to a species of marine mammal with a long dorsal fin, which is not related to any other known whales or dolphins. It is considered to be a member of the dolphin family (Delphinidae). However, it differs from all other members of this group because its head is much larger than that of other dolphins and whales. Its body length ranges between 4.5 m and 6 m, but only 5–6 m are found in captivity.
In the early 20th century, the name “pilot whale” was used to refer to several different species of large cetacean, including pilot whales, minke whales, right whales and beluga whales. They were classified into two groups: the Balaenoptera and the Odontoceti.
The latter two have been shown to be closely related to each other.
A few years ago scientists discovered that there is another new species of cetacean living in the waters off Antarctica. Unlike other whales, which feed on krill and small fish, these whales prefer to eat squid.
They are also smaller than most other species of baleen whales.
In 2006, scientists in Australia completed the first draft of the genome of a pygmy three-toed sloth (Bradypus pygmaeus) found in Central and South America. Since then, they have been trying to complete the entire genome.
The genome of the pygmy sloth is about 1.2 billion units long. This is only about a tenth of the size of the human genome (3.2 billion units).
The pygmy three-toed sloth spends most of its life hanging upside down from tree branches. It sleeps or rests on average for around 15 hours every day.
Sometimes it only wakes up for a few hours every week. It eats leaves, shoots, fruit and flowers.
The pygmy sloth has a low metabolic rate (less than half that of other mammals of similar size). It has a very low body temperature (33 °C) and moves extremely slowly.
Sloths may take up to a month to digest food.
The pygmy three-toed sloth is able to survive in the wild despite its incredibly slow metabolism because it has evolved to have an incredibly low nutrient requirement. It is also the most slowly evolving mammal that has ever been studied, which helps it to survive in its harsh environment.
The pygmy three-toed sloth spends so much time upside down that it actually suffers from back pain. It has to occasionally turn over to relieve the strain.
It turns over by using its claws to hang from a branch or tree trunk and then rotating its body until it is upside down again.
The pygmy three-toed sloth has a particular mating ritual. A male and a female sloth will mate after meeting each other several times on the same tree.
Then, around a month later, the female sloth will give birth while hanging from a tree branch. The baby falls to the ground, but it is not in any immediate danger because the parent sloth will always remain in the same tree.
Sources & references used in this article:
Morphological stages of pilomatricoma by S Kaddu, HP Soyer, S Hödl, H Kerl – The American journal of …, 1996 – journals.lww.com
Pilomatricoma of the head and neck: a retrospective review of 179 cases by MY Lan, MC Lan, CY Ho, WY Li… – … of Otolaryngology–Head …, 2003 – jamanetwork.com
Malignant pilomatricoma by MG Wood, B Parhizgar, H Beerman – Archives of dermatology, 1984 – jamanetwork.com
Giant pilomatricoma by GP Lozzi, HP Soyer, J Fruehauf… – The American journal …, 2007 – journals.lww.com
The common ultrasonographic features of pilomatricoma by JY Hwang, SW Lee, SM Lee – Journal of ultrasound in …, 2005 – Wiley Online Library
Pilomatricoma with a bullous appearance by S Inui, R Kanda, S Hata – The Journal of Dermatology, 1997 – Wiley Online Library