Eaters of the dead

Crawling in a wood in broad daylight, two Arion slugs approach a lucky meal: a dead conspecific. Many snails and slugs are saprophagic, i.e. feed on decaying matter and dead animals. And some of them, like Arion slugs, won’t hesitate to eat dead snails or slugs of their own kind.

Cannibalism in some form or another is not infrequent among gastropods: several snails (including Pomacea bridgesii and other common aquarium snails) will feed on the remains of dead conspecifics, and sibling cannibalism has been observed among hatchlings (e.g. newborns of the common garden snail, Cornu aspersum, will sometimes eat the other eggs that haven’t hatched yet). Few species, however, hunt live individuals of their same species: Schizoglossa novoseelandica being an example. By contrast, despite being known as “cannibal snail”, Euglandina rosea (rosy wolfsnail) will rarely prey upon individuals of the same species.

GLOSSARY

Intraspecific predation: from Latin intra “within”, predation within the same species = cannibalism
Adelphophagy: from Ancient Greek ἀδελφός (adelphos) "brother" & φάγος (phagos) "eater" = sibling cannibalism

Literature:

Life and romance of a one-eyed Roman snail

Or: Reproduction and Birth in Helix pomatia.

Blinded by love? Alezan the burgundy snail (Helix pomatia, a.k.a Roman snail) has only one eye. Whether this is the result of trauma or birth defect, it’s unclear, but one thing is certain: it hasn’t prevented Alezan from living a healthy, functional life – or successfully reproducing, for the matter.

Alezan and Margot, mating. Both adults (and fellow Helix pomatia Blanche, not shown)
were purchased from a snail farm in Austria

Mating in Helix pomatia occurs in a frontal, standing position: the two individuals face each other, their pedal soles in contact. As most land snails, Helix pomatia is an incomplete hermaphroditic species, with each individual having both male and female organs, but unable to self-fertilise.

Laying eggs

After mating, both adults will lay eggs, in a hole several centimetres deep in the ground, where earth is moist and soft. The eggs are fairly large (about 1cm in diametre). Egg laying is a strenuous activity, which may take up to a full day for a burgundy snail.

Alezan’s babies, leaving the nest: it may take the newborns a few days to leave the underground after hatching

Eggs were laid on September 14, and hatched after two weeks. In the wild hatchlings born so late in the year may not survive their first winter.

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Further reading:

Wonders from the East: Amphidromus

Shells like jewels: when we think of fabulous shells with vibrant colours and elaborated patterns, our mind automatically conjures up pictures of marine mollusks… oblivious to the tremendous beauty of certain land species.

(Photo: source)

Amphidromus is among them. A genus of arboreal land snails from south-western Asia, Amphidromus is notable for its large, polymorphic shells, which have fascinated naturalists and collectors since the 18th century.

Dextral and sinistral Amphidromus shells (Photo: source)

Randomly dimorphic coiling? While most gastropod species show a predominance of either right- or left-handed coiling, in a significant number of Amphidromus species, individuals of the same population can be either dextral or sinistral.

Amphidromus adamsi adamsi (Photo: source)

(PS: And I do not know about you, but I find the live animals even more fascinating than their empty shell.)

Literature:

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