On Friday I gave you this rather unusual looking skull to identify:
In fact, it’s so unusual that it doesn’t even look entirely like a skull, so it’s not surprising that the specimen proved a bit of a challenge.
Some elements (like the lower jaw) look a bit like they’re from a turtle, but other elements of the skull shape look more like they belong to an amphibian – from something like Necturus perhaps. Despite these similarities to some of the ‘basal’ tetrapods, the skull is actually from a fish.
The reason why it looks quite similar to a tetrapod skull and less like the average fish is because it belongs to a member of the Lobe-finned fish (Sarcopterygii) which are more closely related to the tetrapods than the more common and diverse Ray-finned fish (Actinopterygii). Despite the difficult identification, microecos managed to spot that this was a Lungfish and henstridgesj managed to identify the species as being the West African Lungfish Protopterus annectens (Owen, 1839) with Barbara Powell and Jake in agreement.
These odd looking fish are ambush predators that grab any small animals that pass by in the murky waters. They have fleshy fins that allow them to manoeuvre around on river beds and in shallow water and mud, which is useful as they often live in ephemeral streams that dry up on a regular basis.
Their modified swim bladder acts as a lung, so they gulp air in order to extract oxygen, rather than just relying on water passing over their reduced gills. This has obvious benefits in an environment that often becomes dry and in water that is very muddy. They also have some other interesting behaviours, like aestivation, to help beat the heat in their native environment, as shown in the video below.
Of all the vertebrates, I find the skulls of fish bear the least resemblance to their living owners (or anything else, for that matter). Considering how streamlined their bodies are (in general), their skulls look as if they were designed with the complete opposite in mind.