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somuchscience:

Happy Father’s Day to You, Seahorses!

by Tami Weiss, FusedJaw.com

Seahorses are often referred to as the best dads in the animal kingdom – and for good reason – they’re the only animal where the male gets pregnant! That’s right, it’s the men that take on the joys of childbirth in these equine fishes.

How does he do it? He has a special patch of skin called a “brood pouch” that the female lays the eggs into. He then keeps the eggs safe until they hatch using a strong muscle to keep the pouch closed. When they hatch, he releases the fry (baby seahorses) to fend for themselves. The fry are exact replicas of the parents, except only a few millimeters long.

Some fun seahorse facts:

1. As few as 8 or as many as 2000 seahorses can be born at one time, depending on the species.
2. The male seadragon and the male pipefish, seahorse relatives, also incubates the eggs. However, another relative, the Ghost Pipefish, the female that incubates the eggs.
3. Seahorses lack a tail fin for swimming. Instead, their tail has evolved to grasp objects to keep them anchored in place. To swim, they use their small dorsal fin on their backs, and steer with their pectoral fins which are located on their head behind their gills. For that reason, they are not very good swimmers.
4. Adult seahorses do not have very many predators. They have bony plates covering their whole body which makes them unpalatable to most fish. The few animals that don’t seem to mind this are crabs, skates and rays, angler fish, tuna, penguins and other sea birds.
5. The first recognized pygmy seahorse Hippocampus bargibanti, a species smaller than your thumbnail, was discovered on accident when a biologist studying the sea fans in the lab noticed this tiny fish that had hitched a ride on the sea fan he was studying.
6. The smallest seahorse known is only 13mm long. Satomi’s pygmy seahorse was only discovered in the past year, and is less than the size of a penny. Its babies (or fry) are about the size of an apostrophy in a newspaper when born.

Read on…

nprglobalhealth:

Chopped: How Amputated Fingertips Sometimes Grow Back

When a kid lops off a fingertip with a cleaver or car door, there’s a chance the end of the digit will grow back. The fingerprint will be gone, and the tip may look a bit strange. But the flesh, bone and nail could return.

Now biologists at New York University have figured out just how this lizard-like regeneration happens in mice. There’s some secret sauce at the nail cuticle that makes it possible, scientists report Wednesday in the journal Nature.

Doctors have seen the effect in humans without quite understanding how it happens. “Kids will actually regrow a pretty good fingertip, after amputation, if you just leave it alone,” say Dr. Christopher Allan, from the University of Washington Medicine Hand Center, who wasn’t involved in the research.

The orthopedic surgeon saw this out a few years ago when an 8-year-old girl stuck her finger into the spokes of her brother’s bike. The wheel sliced off her middle finger, near the nail cuticle, and her parents rushed to the ER to have it sewn back on.

Allan specializes in hand reconstruction, but he couldn’t find the tiny artery he needed to reconnect. So he opted instead for what surgeons call a biological dressing. Just stick the tip back on and hope for the best, he says.

“The girl came back in a few weeks with the old fingertip in a bag and a new one on her hand,” Allan tells Shots. “It was far better than anything that I could have given her with a graft or surgery.”

Scientists see a similar phenomenon with mice paws. But even the elderly rodents can do it, says Mayumi Ito of New York University. “It’s totally amazing,” she says. “The adult mice totally regenerate the organ to its original form.”

But the amputation must leave a little bit of the fingernail — er, claw. And she wanted to figure out why. So she and her team went hunting for the stem cells.

Continue reading.

Photograph of fingernails by Heather Rousseau/NPR. Image of regenerated mouse “fingertip,” left, courtesy of the Ito Lab/New York University. Illustration of the bones in the human hand,right, by LadyofHats/Wikimedia.org.