Whales Are Fish: Weird Perspectives on Classification
You would think that after researching how a species will react to climate change, which individuals are more likely to avoid predators, and what its DNA says about its evolutionary history, simply classifying what species an animal is would be pretty simple. Unfortunately that’s not the case. I distinctly recall being given the runaround by my primary school teacher when asked to define what a mammal was (according to the internet a coconut qualifies, so maybe that debate’s not over yet).
You’d think that once you learn a bit about biology, species classification becomes an easier game. Unfortunately, as with most of academia, there more you find out, the less you know. Debates on whether something is a frog or a toad don’t get resolved, they simply become more sophisticated.
However there are certain things you find out which challenge what you’re taught when you’re younger. Groups that we’re told are separate, to pick apart, when in fact one might fall under the other. Take the dinosaurs for instance. From an early age we’re taught that they died out. Yet the birds lived on, and as many people these days know, the group Aves (birds) makes up a large branch of the dinosaurs.
Yet there is value in making distinctions between modern birds and dinosaurs (many museums now refer to previous mass extinctions as having wiped on ‘non-avian’ dinosaurs). Separating certain ‘taxa’ into different groups, even when there is significant overlap, has obvious benefits when it comes to learning.
So because (and somewhat in spite) of this, let’s look at some fun taxonomic nonsense that challenges what we’re taught as kids. All of these are fun tidbits that have either baffled me or a colleague/friend of mine over the last year or so.
Dogs are Wolves
Turns out that dogs (Canis lupus familiaris) are the same species as wolves (Canis lupus). Unlike the three comparisons below, your opinion on this one really depends on your view of subspecies. A third name tacked on at the end of the species name dictates a subspecies. For example, tigers round the world are also all technically the same species, yet they’re often grouped into different subspecies, largely dependent on their location.
The dogs vs. wolves comparison is particularly striking though, mainly because of the stark difference between a pug and a wolf. It’s hard to reconcile that they’re the same species, especially given how much more similar some other animals that are not even in the same genus can appear. Given the differing regards the two are held in though, it’s hard to argue that we should teach people they’re the same animal.
Tortoises are Turtles
There you go. Next time you mess this up and some jerk coughs and starts their “um, actually, that’s a tortoise…” you can cut them off IMMEDIATELY. Turtles are technically the order of reptiles called Testudines, whilst tortoises are of the family Testudinidae, which falls within that order.
This theme of one group falling within another makes up the next two factoids as well. This one’s pretty mild (and let’s face it, allows us to get one over on pedants everywhere), but as you should see by the last one, there comes a time where science teachers need to draw a goddamn line.
Birds are Reptiles
Adam has already covered this in a previous article (see the link here). As with the earlier birds/dinosaurs example, the group Aves falls under the class Reptilia. However this is where is starts to get dicey. Some scientists still consider birds and reptiles to be separate classes. Opinions here tend to get divided based on the party’s approach to taxonomy. Using cladistics (relating species by their most recent common ancestor), birds are technically reptiles (we’ll write more on this soon – it may be a whirlpool of arguments and vernacular, but it’s an interesting one).
Yet again, owing to the obvious differences in appearance and life history, most reptiles are often grouped separately from birds (including in yesterday’s Paper of the Week), despite the fact that most systems of classification consider crocodiles more closely related to birds than lizards.
Whales are Fish
Well if you want to get technical (in a very loose definition of the word), so are we. Talk about drawing longbows.
The Sarcopterygii are a group of fish, which evolved into the first land-dwelling tetrapods, which went on to include whales (and us). There are actually only a few non-tetrapod species – the coelocanths and the lungfishes.
Educationally, this is an interesting one. Whilst teaching kids that all those animals they’re looking at are just highly evolved fish doesn’t really teach us much about identification, it can teach us a lot about evolution.
These are far from the only fun cases out there. Mountain goats don’t technically belong to the goat genus (Capra). Toads are grouped within frogs, so it’s easy to simply dismiss toads as a type of frog, as opposed to a separate group (much like the turtles/tortoise argument). The list goes on.
It’ll be interesting to see whether or not concepts like those above are integrated into modern teaching. It is of course possible to teach kids that there are differences between two groups, while teaching them that there is significant overlap between them. However I’m no primary school teacher, but given that I still struggle to figure out how to classify sea-bound and river-bound brown trout, maybe it’s not that easy.