Normal frogspawn consists of a central embryo surrounded by a clear jelly-like capsule. When laid, the embryo is dark brown-black, with a creamy white underside which turns dark after a few days. Normally this underside is not visible to us unless the spawn clump has been overturned, so don’t be concerned if you see partially light-coloured spawn just after it has been laid.

Reasons for spawn failure:

• Late Frosts : unusually warm periods coming out of winter can cause frogs to spawn early. If the weather rapidly changes and overnight frosts occur the spawn can freeze and kill the developing eggs. If it is a light frost sometimes only the spawn closest to the surface will be killed, the rest may survive as it is more insulated from the cold.  
  

• Unfertilised spawn : some spawn is laid partly or completely unfertilised and so will not develop at all. The spawn will have a normal “jelly” appearance but will become cloudy and fungus may infect it as it rots.   
  

• Fungus : if we have a particularly cold spring you may find spawn in your pond covered with a white thread like feathery fungus that looks not unlike cotton wool. It often occurs when spawn has been killed off by late frosts, although there may be other reasons for this phenomenon that Froglife are looking into. 
  

• Predators: all amphibian life-stages form a natural part of the food chain. Spawn is probably the life cycle stage that is safest from the attack of predators. However newts, moorhens, flatworms and fish will all eat spawn. Usually dead eggs will have grey or white centres; however live eggs with all-white centres very occasionally develop into albino tadpoles and froglets.

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