Star Jelly: The foul-tasting and unusual white jelly you may spot around Yorkshire

Brian Morland finds an unusual substance in a nearby quarry and looks at the difficulties a frog has to endure in just staying alive.

Since November last year I have been finding clumps of clear, white jelly substances around the restored quarry site. Most have been on the ground, but one clump of jelly was on the top of a fence post.

These jelly substances are referred to as "Star Jelly”. There is a huge amount of folklore about Star Jelly dating back to the 14th century.

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It was suggested it is deposited on the Earth during meteor showers. It is described as a white, translucent, gelatin that tends to evaporate shortly after having “fallen".

“Star Jelly” is all that remains of a large female frog.“Star Jelly” is all that remains of a large female frog.
“Star Jelly” is all that remains of a large female frog.

Sir Walter Scott in his novel The Talisman wrote about Star Jelly. Rather sadly, there are even people in these enlightened times who believe in the astral explanations.

Eighteenth century naturalists Thomas Pennant and Gilbert White were basically correct when they described Star Jelly as something vomited up by birds and animals.

Star Jelly is what is regurgitated, or rejected by a predator eating a female frog just prior to spawning time. In simple terms, it is frogspawn without the eggs.

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If a predator dismembers a frog, the ovary will be torn apart, releasing the eggs close to the oviduct remnants.

A full-grown common frogA full-grown common frog
A full-grown common frog

The oviducts may be stimulated to release their jelly-like glycoprotein by the trauma of the attack. Since it does not have the eggs, it emerges as an amorphous mass and will absorb water from the soil, or rain and swell, producing the large jelly masses that people find.

This jelly must be extremely distasteful to all predators. Birds will regurgitate it and probably animal predators carefully avoid eating the oviduct.

The foul taste explains why I have never recorded it being eaten, or even disturbed. A clump of frog spawn, when fully expanded, is many times the size of the frog that produced it.

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The clump of Star Jelly I found on a fence post was probably regurgitated by an owl, or carrion crow. As most frog predation is after dark, my money would be on a tawny owl.

A froglet.A froglet.
A froglet.

The Star Jelly in the photograph is likely to be all that remains of a large, female frog eaten by a badger. Fresh badger “snuffle holes” were recorded close to the Star Jelly.

The Common Frog Rana temporaria is exceptionally abundant on the restored quarry area in the smaller lakes that are surrounded by marginal vegetation. The favoured spawning site is in shallow water amongst collapsed willows at the southern end of the main reedbed.

Large quantities of spawn appear every March in this area. Once the tadpoles emerge, there is plenty of cover amongst the collapsed willows and red, fibrous willow roots for them to shelter from predators.

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As the shallow water warms up, there is also plenty of algae and detritus for the tadpoles to feed on. The main predators of tadpoles are birds. Herons are the obvious predator of adults and tadpoles.

I can never understand why management groups want to remove all vegetation from the margins of a pond, or lake.

All this achieves is allowing unfettered predation of everything in the margins of the water. I once watched a pair of jackdaws that had found a group of tadpoles in very shallow, open water on a lake. In three days, they had cleared the lot.

As the tadpoles develop into tiny frogs after about 14 weeks, they need marginal cover to emerge from the water onto the land.

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Froglets, for want of a better word, are a food item for many species. I once found a few tiny frogs in a field, over 100 metres from water. Two of them were on their backs, still alive, but having had their legs partly eaten. I was puzzled to what had done this. Later in the day I passed by again and caught the culprit in the act of leg chewing. It was a common shrew.

I have heard it suggested that fish in a lake, or pond are the biggest threat to frogs and other amphibians. Fish will obviously eat tadpoles, but as soon as they emerge, most of them congregate in the margins, often too shallow for fish to venture.

Without bankside vegetation, tadpoles are easily “picked off” not just by water birds, but also by crows, jackdaws, magpies and even blackbirds. A large, fully grown frog is an impressive animal, but very few ever achieve full size.

In hot weather during the summer, frogs will hide away under cover where it is cool and damp during the daytime.

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After dark, they emerge to feed on the many invertebrates encouraged by the hot weather. During the excessive heat in July 2022, I found a great many frogs feeding on ground beetles and craneflies after dark, by walking over rough grassland with a lamp.

I run moth traps most nights and those located near the lakes are visited nightly by frogs attracted by all the moths and sedges.

If you want to increase amphibian numbers around a lake, stop being neat and tidy. Just let cover develop naturally. Constant removal of vegetation and grass cutting is called gardening!

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