It’s been too long since we had an episode about whales. Yes, okay, two weeks ago we talked about a couple of newly discovered whales, but I want to really learn about a particular whale. So this week, let’s look at the fin whale.

The fin whale is a baleen whale that’s only a little less enormous than the blue whale. The longest fin whale ever reliably measured was 85 feet long, or just a hair shy of 26 meters, but there are reports of fin whales that are almost 90 feet long, or a bit over 27 meters. An average American school bus is half that length, so a fin whale is as long as two school buses. Even a newborn fin whale calf is enormous, as much as 21 feet long, or 6.5 meters. Females are on average larger than males.

It’s a long, slender whale that’s sometimes called “the greyhound of the sea,” because it’s also really fast. It can swim up to 29 mph, or 46 km/hour, and possibly faster. If that doesn’t sound too fast, consider that the Olympic gold-medal swimmer Michael Phelps topped out at about 4.7 miles per hour, or 7.6 km/h.

Like other baleen whales, the fin whale has a pair of blowholes instead of just one. On its underside, it has up to 100 grooves that extend from its chin down to its belly button. Yes, whales have belly buttons. They’re placental mammals, and all mammals have belly buttons because that’s where the umbilical cord is attached when a developing baby is in its mother’s womb. I don’t know what a whale’s belly button looks like. Also, the proper term for belly button is navel, and if you’re wondering, that’s where navel oranges get their name, because they have that weird thing on one end that looks like a belly button. It’s not, though. I don’t know what it is. You’ll have to find a podcast called Strange Plants to explain it.

Anyway, the grooves on the fin whale’s underside act as pleats, or accordion folds. Other baleen whales have these pleats too. A baleen whale eats tiny animals that it filters out of the water through its baleen plates, which are keratin structures in its mouth that take the place of teeth. The baleen is tough but thin and hangs down from the upper jaw. It’s white and looks sort of like a bunch of bristles at the end of a broom. The whale opens its mouth wide while lunging forward or downward, which fills its huge mouth with astounding amounts of water. As water enters the mouth, the skin stretches to hold even more, until the grooves completely flatten out. The water it can hold in its mouth is about equal to the size of a school bus.

Technically, though, a lot of that water isn’t in the whale’s mouth. It’s in a big pocket between the body wall and the blubber underneath the skin. The ballooning out of the pocket stretches the nerves in the mouth and tongue to more than twice their length, and then the nerves have to fold back up tightly after the water is pushed out. The nerves fold in a complicated double layer to minimize damage during all this stretching.

After the whale fills its mouth with water, it closes its jaws, pushing its enormous tongue up, and forces all that water out through the baleen. Any tiny animals like krill, copepods, small squid, small fish, and so on, get trapped in the baleen. It can then swallow all that food and open its mouth for another big bite. Even more amazing, this whole operation, from opening its mouth to swallowing the food, only takes six to ten seconds.

Because it only eats small animals,

Rate