odontocete

While trying to wrap my head around a billion other projects, I felt urged to loosen up a bit and painted this on a 12 x 24 inch canvas. It’s a revisit to an old digital piece I did in 2009, but I’d always liked the composition and wanted to explore it using traditional media. There are so many gorgeous photos, paintings and illustrations of orcas breaching, but I always find myself thinking about the view from under the water. I love how water behaves around marine animals at the surface.

www.jenrichardsart.com

Repeat after me: 

Blackfish is not about making SeaWorld trainers look bad.

Blackfish is not about making SeaWorld trainers look bad.

Blackfish is not about making SeaWorld trainers look bad.

There’s no denying that the trainers love the whales. We get that they’re in it for the animals, not the money. We’re not disputing that. That’s not what the film is about. So let’s bring the debate back to the whales, not the trainers, please. It doesn’t matter if the trainers have good intentions, or care for the whales with all of their hearts, when the whales are still living in a substandard captive environment. 

The film is not challenging how much the trainers love the orcas. It is challenging the actual conditions the orcas are living in.

Whalevolution Month #22 – Janjucetus

Living around southeast Australia 25 million years ago, the 3.5m long (11′6″) Janjucetus had large eyes and jaws full of sharp teeth, and may have been an active hunter in a similar niche to modern leopard seals.

But despite sounding like it should be some sort of proto-orca, it wasn’t even an odontocete. This was actually a baleen whale, albeit a member of an odd group that split off before the development of baleen and kept their teeth. Both Janjucetus and its close relative Mammalodon had wide blunt snouts and very large mouths for their size, suggesting they were specialized for suction feeding – using water pressure to draw prey straight into their waiting jaws.

Odontocete anatomy

Just a little bit about echolocation:

Odontocetes are the only marine mammal that can echolocate. The whistle and click producing structures are located in the nasal sac system just inside the blowhole. The structures are known as the monkey lips/dorsal bursa (MLDB) complex, and it has been hypothesised that sounds are generated as air is forced between the phonic (monkey) lips setting the MLDB complex into vibration (Cranford et al. 1992). The sounds are then reflected by the cranium and focused into a ‘beam’ by the melon (a fatty structure located in the forehead serving as an acoustic lens). These high frequency echoes are then received through the hollow mandible then transferred across fatty channels to the middle and inner ears. 

Whalevolution Month #15 – Squalodon

An early member of the odontocetes, Squalodon was a basal member of the Platanistoidea branch of the toothed whales – represented today by the river dolphins, but originally widespread throughout marine habitats before the rise of the modern oceanic dolphins.

At least seven different species of Squalodon are known from around the world, including Europe, eastern North America, New Zealand, and Argentina, dated to between 34 and 15 million years ago. The largest would have been around 3m long (9′10″), and the tips of their jaws featured protruding tusk-like teeth. Their skulls also show some of the earliest evidence of the development of echolocation.

Post #1: Whales

Whales are fully aquatic marine mammals. This means they live in the sea and give labor to living creatures, so they don’t lay eggs. Another example of a mammal that lives under water is a dolphin. Whales belong to the clade Cerartiodactyla (even-toed ungulates) and a very close relative is the hippo! There are 40 species of whales, for example: the gray whale, the beluga, the beaked whales, … Whales can be separated in two suborders: Odontocetes and Mysticetes. The Odontocetes are the toothed whales and the Mysticetes are the baleen whales. This means they have a whole other way of eating and living!



Keep reading

Whalevolution Month #17 – Simocetus

Simocetus lived around the Pacific Northwest of the United States about 32 million years ago. Roughly the side of a modern bottlenose dolphin – estimated about 2.5m long (8′2″) – this odontocete is known from a fossil skull and a few other fragments discovered in the 1970s but not officially described until 2002. It had a mixture of primitive and specialized features, indicating it was closely related to the most basal of the toothed whales, but its skull structure suggests it already had well-developed echolocation ability.

Its jaws were also partly toothless and oddly downturned, which has been interpreted as an adaptation for suction feeding – sucking in a mixture of sediment and soft-bodied invertebrates from the seafloor and straining the food out between its sieve-like teeth.

Yes. A filter-feeding dolphin.

Whalevolution Month #19 – Cotylocara

Only discovered last year (2014), Cotylocara is known from South Carolina of the United States, about 28 million years ago. Roughly 3m long (9′10″), it was a member of a somewhat obscure clade of early odontocetes called the Xenorophidae – one of the very first groups to diverge, and probably about as distantly related to modern forms as it’s possible to be while still being a member of the toothed whales.

Its skull indicates it possessed at least a rudimentary form of echolocation. Since it was so distantly related to other toothed whales, this gives strong evidence that echolocation was a truly ancestral trait for all odontocetes, originally developing in their common ancestor at least 34 million years ago.