26 November 2007

Things inside a skate egg case

SkateEggcase1

These characteristic egg cases of skates were common on the Atlantic side of the beach at the Chincoteague National Wildlife Refuge last month. I don't know which species they belong to. According to Lippson & Lippson (Life in the Chesapeake Bay, 2nd. ed., 1997), the clearnose skate (Raja eglanteria) is found near the south end of the Chesapeake Bay. Chincoteague is on the Atlantic coast and these egg cases may belong to the same species of skate and they indeed resemble the drawing of the egg case of the clearnose skate given at the link above.

The baby skates develop inside these cases (apparently one skate per case) and come out when they are ready to face the challenges of the outside world. I took one specimen that appeared intact.

SkateEggcase2

This one didn't look like it was ever opened. So I was hoping to find tiny bones inside.

When I removed one side of it, there were these tiny rings, a few spine-like objects and some sand grains.

SkateEggcase3

I don't know what those rings are. They are about 0.8 mm in diameter. Could they be skate vertebrae?

SkateEggcase4

4 comments:

pascal said...

It's possible. Sharks and rays are chondrichthyans which means most of their 'bones' are cartilage. However, some species have calcareous vertebrae. They look somewhat like other shark vertebrae I've seen.

Roger B. said...

Having eaten "skate's wing" in a Cornish restaurant, I can confirm that that their bones are relatively soft.

Skates' egg cases are known as "mermaid's purses" on this side of the Atlantic.

John said...

In the last photograph, they look a bit like pasta.

Tara @ Feels like home said...

This is very cool! We found a skate egg case on the New Jersey shore a few weeks ago, and we were confused because it didn't seem to have a hole in it any where. We're torn between leaving it in tact and checking out what's inside. From the sounds of things (when we shake it, I mean), it could be something similar to yours. Thanks for sharing!