#true tunas

[uncharismatic-fauna]

Uncharismatic Fact of the Day

Most fish are cold-blooded, but bluefin tuna are an exception. These fist have a blood vessel system known as a countercurrent exchanger. A mesh of veins and arteries circulate blood near the surface of the fish’s skin; the veins capture heat generated by an individual’s metablism, and the arteries transfer that heat back into the body. The system is not foolproof, and tuna are not wholly warm-blooded, but it does allow them to survive in much colder temperature for much longer than other fish species, and it makes them much more effective hunters.

(Image: A school of bluefin tuna (Thunnus thynnus) by Ugo Montaldo)

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[uncharismatic-fauna]

Uncharismatic Fact of the Day

Tuna fish might be a tasty meal for us, but in the wild they’re the ones at the top of the food chain. Each of the 15 species of tuna fish in the genus Thunnini preys on a variety of fish, squid, and crustaceans, and are often the first ones on the scene of a feeding frenzy. Part of what makes them such good hunters is their speed; some tuna have been clocked at over 70 kph (43 mph)!

(Image: A school of Atlantic bluefin tuna (Thunnus thynnus) by Brian Skerry)

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