Big Skate
Raja binoculata
The big skate is known to be the largest skate in the eastern North Pacific Ocean., Their maximum size has been noted as 244 cm total length (TL), but the largest confirmed size is 203.9 cm TL.
- The fresh egg cases of the big skate, like the one shown below, were taken from dead gravid females that were caught in commercial groundfish fisheries.
- Their egg cases are larger than most other skate egg cases; typically ranging from 210 to 280 mm in length and 110 to 180 mm in width.,
- The egg case is very smooth and lacks external fibrous material. This egg case can be easily identified from all others in that it is the only one to have a steep ridge; giving the case a convex shape.
- The keel on the egg case is considered very broad; representing 30-33% of the width of the egg case.
- Egg cases, in utero, are found in pairs.
- Big skates are one of only two skates known to have multiple embryos inside an egg case; up to 7 embryos have been found inside a single case. But most big skate egg cases contain 3-4 embryos.
- Big skate have a 70 mm difference between the smallest and largest egg cases; this is uncommon in most skate species. Research is currently being conducted on whether or not a relationship exists between egg case length and the overall size of the female big skate. This may answer questions like "why does a larger disparity exist between the minimum and maximum sizes of egg case length of the big skate versus the other skate species"?
- Big skates egg cases are approximately 15% of the overall length of the female skate.
- The color of the egg case is olive green, when fresh, and it turns to a dark brown as it ages. Dried egg cases often turn black and wrinkle up (See image below).
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Egg case of the Big skate, Raja binoculata
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Four embryos inside a big skate egg case
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Big skate egg cases; Egg case on left is fresh and older ones are to the right
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Roughtail egg case Bathyraja trachura
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The eggcase of a Raja species, probably Raja undata
Read more about this topic: Egg Case (Chondrichthyes)
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