#tursiops truncatus

Two species of bottlenose dolphin in Eastern Australia

These are two older illustrations I recently revamped. I really like how they turned out so I decided to make a little infographic. The distribution and ecological interaction between these two species is very interesting. In many places, two types of Common bottlenose dolphin exist:

• The coastal / inshore type, which inhabits small ranges in (very) shallow water
• The oceanic / offshore type, which inhabits very large ranges in deep water

The oceanic type can appear quite close to shore in places where the seafloor quickly drops (here the coastal type is often absent), but in most areas with extended shallows the coastal type will make its home. However, once you enter the range of the Indo-pacific bottlenose dolphin, the coastal type disappears. Indo-pacific bottlenoses completely fill their coastal niche, and only oceanic-type Common bottlenoses remain. This situation is very noticeable in Australia, which these illustrations are based on.

It’s interesting to note though that coastal Common bottlenose dolphins from warmer waters can look incredibly similar to Indo-pacific bottlenoses: including a longer beak, large fins and spotted undersides (which are usually seen as Indo-pacific-specific traits). Curiously, spotting is actually absent on Indo-pacific bottlenose dolphins from the southern half of Australia.

A posse of proper ‘phins
And another set of illustrations from last year. This time the “proper” dolphins - not too small, a regular dorsal fin, a good beak. Only the Risso’s is a bit out of line with their cute potheads but otherwise he was all alone. I had lots of fun with all of these. Spinners and Pantropcal spotted dolphin are a delight to draw always. This Pantropical spotted is from the Indian ocean, which tend to have fine black spots and very few white spots. The rough-toothed dolphin gave me some trouble - they’ve such odd proportions they’re hard to really nail down. I still don’t think he fully looks right, but that’s for a different illustration.

The common dolphins on top are very interesting to me: a good example of the diversity found within the single species of Delphinus delphis. Both are forms living around Southern Africa. The “longer beaked” form is larger, more elegant, and has gorgeous clear markings. They live off the Southeast coast, relatively close to shore. The “shorter beaked” form lives more to the west, in offshore waters. They are stouter and often with slightly vaguer markings. One day I’d love to see a study done on all the African forms of short-beaked common dolphins, they are so fascinating. If you move further up the west coast, around Angola, you’ll find a really strange form which is super dark and oddly proportioned. Wonder what’s up with those.

The Indian Ocean humpback dolphin is also an oddball, and a first for me. Love their cute faces and unique body shape. Not just the hump-back but also that strongly keeled peduncle. I hope you’ll enjoy them too!