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Fish Eggs,  Embryos and Larvae

Transparent Fish Eggs, one a developing embryo, from the open sea. Note the oil drop

Marine fish have a planktonic larva. Either the eggs will be sticky and laid on the shore, e.g. sand eels, or for those living further out at sea 1000s of transparent eggs will be released into the water. The latter are the ones seen here. Only about 20-30 appeared in an autumnal sample and must have been brought in by the tide. One of the eggs has a developing embryo. Each egg has a strong outer chorion coat and is around 1 mm in diameter. Distinct in the photo is the presence of a drop of oil on the developing egg. Along with the yolk within the chorion the oil will also be consumed as food although it probably helps with buoyancy. 

Tail of developing fish embryo with oil drop
Fish embryo within the egg, possibly Sand Eel

A well developed fish embryo, possibly a Sand eel.

Developing marine fish embryo

Fish Larvae

Fish larvae possibly Sand eel
Marine Fish larva in plankton sample

These fish larvae appeared in the Dale samples just once in 5 years. The white ones are abundant off Skomer in spring and autumn. Possibly Sand Eel larvae. 

Sand Eel larva

© 2025 Julian Cremona

All Photographs are Copyright Julian Cremona

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