Showing posts with label senses. Show all posts
Showing posts with label senses. Show all posts

Sunday, 16 August 2026

Otter Whiskers

Four years ago, I posted about whiskers, a feature common to the majority of mammal species, from horses to mice. They are so widespread that they must have evolved very early on, probably well before marsupials diverged from the placental mammals, back in the time of the non-avian dinosaurs. Even so, as humans, we are probably most familiar with them from domesticated animals, especially the carnivorous ones that so often share our homes.

The carnivorans form a natural evolutionary group within the placental mammals, arbitrarily (if conveniently) ranked as an "order". The various living families within this order can in turn be classified as either "feliform" or "caniform", depending on whether they are more closely related to cats or dogs. The dog-like group contains a great many species, which might be more varied than we would think at first glance.

Sunday, 16 January 2022

Why Animals Have Whiskers

One of the key defining features of mammals is that they have hair, or are at least descended from other animals that once had hair. The primary purpose of hair is to keep the animal warm, something useful for any warm-blooded animal, especially if it's small (elephants and rhinos, for example, while they do have hair, aren't really what you'd call "furry"). But, over millions of years of evolution, hairs have also evolved to carry out other functions, such as the protective spines of hedgehogs and porcupines.

Another example of specialised hair is that of whiskers. Technically known as vibrissae, whiskers are remarkably common in mammals. When we think of whiskers, it's likely that most people's thoughts jump immediately to the long, mobile, whiskers of cats and mice. But whiskers can also be shorter and less mobile than this, as we see in such animals as horses. Indeed, even if we look at a cat, whiskers are not restricted to the long ones on the snout; they also have whiskers on the eyebrows, on the cheeks and chin, and on their forelegs just above the paws. 

Sunday, 2 May 2021

Mammals That Sense Magnetism

Traditionally, there are said to be five senses: vision, hearing, taste, smell, and touch. From a modern scientific viewpoint, however, this is clearly a significant underestimate, since things are rather more complicated than that.

How many senses even a human can be said to have is a matter of definition, although it's generally agreed to be more than five. An extreme way of counting would be to consider every specific type of sensory cell as representing one 'sense'. This, however, results in the conclusion that vision is four separate senses: one for black-and-white (the rod cells) and one each for the primary colours (the cone cells). This, it's probably fair to say, is not something that's widely considered helpful - although it may well be useful to neurobiologists.

If we don't go that far, then, we can still consider vision, hearing, taste, and smell to be singular senses. It is, however, not uncommon to consider the ability to sense temperature as distinct from the ability to sense that you are physically touching something. Pain can also be considered a distinct sense, since you can obviously 'feel' when you have, say, a headache, but it's hard to argue that that should count as 'touch'.

Sunday, 1 July 2018

Fishing in the Ganges

The most spectacular cetaceans are, arguably, the really big ones - sperm whales, blue whales, and so on. However, while our knowledge of the exact numbers is a little hazy, somewhere around half of the cetacean species alive today represent much smaller animals. The majority of these belong to just two taxonomic families.

By far the most numerous are the "true" or "oceanic" dolphins, a family that also includes killer whales and pilot whales - small in comparison with the like of humpbacks, but fairly large by most standards. The second family are the porpoises, which are exclusively small, by cetacean standards, and usually slightly smaller than dolphins.

But there are a few small-sized cetacean species that fall into neither group. These oddities share one thing in common: they don't live in the sea. While they are, of course, just as fully aquatic as their better-known kin, this has lead to them receiving the common collective name of "river dolphin", thus distinguishing them from the "oceanic" sort that most people are more familiar with.