The blog Star-Gazy Pie (it's namesake being this whimsically disturbing fish dish from Wales Cornwall) offers up some fun insight into the biology of the tuna—specifically, why that biology makes the tuna so much fun to eat. The piece also explains why certain species of tuna are endangered and how to make sure the tasty tuna you eat was raised in such a way as to ensure that our great-grandchildren will be able to enjoy it, too.
But yeah, have you ever wondered why tuna steaks look like this (top) and say, catfish fillets (bottom) look like this?
DING DING DING: Tuna have more red muscle than other fish in order to fuel their eternal swim (like sharks, tuna literally do not stop swimming). To burn the oxygen required by these hefty piscine muscles, tuna have myoglobin, a type of protein, in their muscles. Myoglobin actually forms the pigments that gives raw "red" meat its color, and is also responsible for making red meat that has been frozen turn brown.
Awesome! Along with that, I also learned that tuna are neither, strictly speaking, cold-blooded OR warm-blooded. Instead, tuna use a network of veins and arteries to trap body heat. They can't regulate their temperature as well as warm-blooded species, but they can stay significantly warmer than the ice cold waters they swim through. Cool stuff.
(Via hectocotyli)
