Genus Kogia - the little Sperm whalesAnd another infographic. I’m really liking this way of sh

Genus Kogia - the little Sperm whalesAnd another infographic. I’m really liking this way of showing off work, feels a bit more visually appealing than just bare illustrations. This time it’s the turn of the mini sperm whales. Even though they look somewhat similar to Sperm whales, they are in a separate family, Kogiidae. It’s interesting how often they strand, given their low sighting rate at sea. They may simply be overlooked or misidentified: they tend to keep a low profile, and aren’t very demonstrative (though Dwarf sperm whales occasionally breach).Even when stranded, the two species can be surprisingly difficult to identify. The most obvious difference lies in the size and position of the dorsal fin. A useful tool on ‘textbook’ individuals, but some animals have a relatively big/small dorsal fin for their species, positioned more in the middle. Another ID tool lies in their markings. Quite noticeable is the ‘false gill’ both these species have - a possible form of Batesian mimicry to look like a shark. In the Pygmy sperm whale this gill mark takes a sort of bracket shape, with a recurved bottom, while in the Dwarf it tends to be straight. There might be a slight difference in overall body markings as well, and from what I’ve seen Pygmies seem to have a somewhat longer head than Dwarfs, but this would be hard to use in the field. Interestingly, some Pygmy sperm whales turn up with more contrasting colouration and speckles all over. Perhaps older individuals? Also, both have these dark ‘eye patches’ which I think is very cute. I hope you enjoy and maybe learn something new about these mysterious whales! -- source link

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