INTRODUCTION |
Skates (order: Rajiformes) are flat bodied elasmobranch fishes, which inhabit the bottom of the seas. They lay eggs (often called "mermaid's purses", "devils purses" or "widow purses"), which are each unique on species level. Although we know the number of present day living skate species (at least 238), the egg-capsule of most of those species is unknown. There is still much to discover. All skate egg-capsules have the same basic plan. The egg-capsule is a rectangular body with a horn on each corner. Sometimes however, the horns are less visible.
Sharks are not all egg-laying. In fact, most well known sharks, like the white shark, the tiger shark and the hammerhead sharks, are life-bearing. Egg-laying can be found in some small families (e.g. bullhead sharks) and the large family of the catsharks. As in skates, each egg-laying shark has its own unique egg-capsule. However, there is a lot of variation in egg-capsule form between the different families. Therefore, each egg-laying shark family has its own webpage on this web-site .
| The egg-capsules of the thornback ray (Raja clavata) (left) and the small-spotted catshark (Scyliorhinus canicula) (right), washed ashore on a beach in the Netherlands. Note that one of the egg-capsules of the thornback ray is deformed!
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| Closely related to the Elasmobranchii, the Holocephali lay also eggs. Here is the egg-capsule of Callorhynchus millii. This picture is made by Jason Caruso (Melbourne aquarium). |
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| the egg-capsule of Raja microocellata with embryo. The embyo will leave the egg-capsule by breaking its way through the field between the long horns. However, hatching can take more than a year!
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