Natures wonders: dolphins strange adaptations (Introduction)

by David Turell , Sunday, May 06, 2018, 16:17 (2391 days ago) @ David Turell
edited by David Turell, Sunday, May 06, 2018, 16:24

Like whales, to enter the water, enormous adaptations had to occur:

http://nautil.us//blog/what-is-it-like-to-be-a-dolphin?utm_source=Nautilus&utm_camp...

"We diverged from dolphins and whales (collectively called cetaceans) only about 65 million years ago, about as far removed as any two mammals can be. (Cetaceans’ closest living relative is the hippo, from whom they diverged about 55 million years ago.)

"So in order to understand a dolphin’s experience, assume you know nothing, basically. You’ll naturally start to empathize—or at least project. That’s natural. Humans can’t really help it. We do it even when we’re getting it wrong. So try to empty your mind. Sit back, relax, and imagine you’re weightless. Gravity doesn’t affect you like it does those land critters. You move in all directions—up, down, left right, in and out of water—all the time. And unlike them, your respiration isn’t automatic, like a heartbeat or a reflex: To take a breath, you have to make the conscious choice to find the edge of the water, your home, every five minutes or so. And because of that: You never sleep. Not really. One half of your brain is active all the time, even when you rest; you literally sleep with one eye open.

"You have good eyesight, both in and out of the water, which is rare in the animal kingdom. You might see color but maybe not—it’s complicated. You lack olfactory nerves, so you don’t have a sense of smell (your air-to-nostril time is exclusively for breathing). The jury’s still out as to what and how you taste.

"You do have excellent hearing: Your auditory nerve has several times as many fibers as humans, and with each fiber measuring about two times thicker, you can hear a range of frequency seven times wider than a human’s. You can even “see through” things, using sonar: Different materials return sound differently, so you can find the fish hiding in the sand, or the shark lurking in the kelp forest. It might even be as detailed as those sonograms humans show off of their unborn children. In fact you can “see” a human fetus inside its mother’s womb (probably). (Maybe you recognize it as a mammal fetus and swim in to get a closer look, causing humans to start a whole “dolphin midwifery” thing, which—just—they need to stop.) It’s possible that your senses of hearing and touch are intertwined: Your jaw, for instance, acts kind of like a tuning fork, helping sound waves up into your “ear”.

"Even though your skin is 10-20 times thicker than terrestrial animals, it’s extremely sensitive. It’s just stupid with nerve endings, especially around the fins, genital region (like humans, sort of), and the rostrum (your snout). You use it to root for food, but most often to touch other dolphins. You use touch to talk. You vocalize, sure, with whistles, screams, chirps, but you use your body, too—for instance, the meaning of petting via pectoral fins may even transcend species.

"Love and friendship are human words that mean nothing to you. But if you see a dolphin you haven’t seen in awhile, you remember them—even decades later. And when someone in your family dies, you notice. And partnerships certainly abound in your world: Females form “alliances” to take care of young, which includes defending against male alliances, whose primary function often involves helping each other fight for the right to mate with females, even perhaps killing the offspring of males from competing alliances. But the rules within these alliances are extremely complicated, the source of articles upon articles trying to decipher their structure. Maybe, some humans say, your emotional intelligence is through the roof.

"Maybe you didn’t evolve a prefrontal cortex (which is the part of the brain humans use to help them regulate their behavior and make decisions). Maybe instead your brain developed a structure called the paralimbic cortex, which could be similar, only everything that goes on there is much more tied to emotion. It’s also a controversial possibility that you have way more of certain type of brain tissue (“association cortex”) that helps sort through sensory input and emotions, and social goings on.

***

"You and your pod-mates have “signature whistles,” patterns that are consistently associated with individuals, used to broadcast your identity, perhaps, like a name.

***

"there are 36 species of dolphin, depending on how you count them. All of them, though, live with 360 degrees of sensory information 24 hours a day, two types of sight, a dozen types of sounds, and more feels than we can imagine. "

Comment: This article covers a tiny portion of the physiologic changes to make a dolphin. They have many other adaptations related to birth and nursing under water, as well as changes in control of salt, since they live in salt water and receive excessive amounts of sodium. Like whales they are a weird result of evolution.