Tuesday, February 3, 2009

Tuesday and Mermaid's Purses

Today the NW wind was pretty strong and there was no doubt that it was coming from the north, because it was chilly. The low temperature was 52 and only 63 for the high. The sunshine felt warm, if you could find a place out of the wind.

After getting out to run a couple of errands anyway; made a stop at West Gulf Drive, Resident Beach Access #2. Taking a quick look around, it was obvious that there wasn't much in the way of shells in this area. After walking a short distance in each direction and taking a video and one photo, I was ready to get out of the wind. Maybe tomorrow there will be more to see.

The one photo that I have, is of two skate egg cases or sometimes called “mermaids purses”.

They are fairly common here, but I have only seen a few of them before. They look kind of leathery and are black in color. They have tendrils sticking out from each point. These are curved like a hook, which catches on seaweed, rocks or sand to anchor them. There is a yolk similar to an egg yolk inside and an embryo. The embryo uses the yolk for nourishment and developes inside the egg case. There is a nice video showing a baby skate hatch. The video will also give you an idea of what a skate looks like if you haven't seen one before. The video is actually of a skate in the North Atlantic, but it shows it so well, that I used it anyway.)

Never having seen one up close and personal, I didn't know very much about them, so I did some hunting and lots of reading. This is an overview of what I learned.

Skates are closely related to sharks and rays and can be found in shallow or deep sea water. The live on the bottom of the sea floor because, like sharks, they have no swim bladder to help them stay up in the water. They have very large pectoral fins that connect the head to their body. The rounded fins, give them a flat disk like appearance. Their entire skeleton is cartilage. The eyes are on the top of their head and the mouth is on the underside. They have a very thin tail with fins at the end that they use as a rudder to steer with. Their body is covered with tiny spines. Many skates have a line of larger spines that runs down the middle of the tail, that are used to defend itself against attackers. A skate can grow to a little over 16 feet, but most are smaller, around 3 feet in length. They locate prey with electric organs found in their tail. Their food consists of a variety of mussels, clams, snails, and worms. Being egg layers, the females during breeding season, store sperm to fertilize and secrete eggs continually through the following three or four months. They can lay a pair of eggs every 3 to 5 days and possibly produce 30 to 40 pairs of eggs. There seemed to be a lot of different facts about the length of hatch time. I read that it takes about 12 weeks for the eggs to hatch on one reputable site and 5 to 6 months or longer on others. The baby skate is a miniature of the adult, measuring aproximately 4 inches long.


George said...

Thanks for a very informative post. I'm not sure I was aware of skates before or of Mermaid's Purses.

Snowbird said...

Cool! Thanks for the info, Tootie. The video of the skate hatching was amazing. I have a really nice skate case. I wonder if I got it pre or post hatch??

Melli said...

We have a huuuuuge display of live skates at our wee little museum down on Solomon's Island. I love to watch them swim! They run rampant in the Chesapeake Bay too -- but I've NEVER heard of their little egg sacks being called a Mermaid's Purse! How sweet!