Molluscs, Annelid Worms and Crustaceans

Our most common - or at least most obvious - molluscs are probably the Garden Snail Helix aspersa, together with Brown-lipped Snails Cepaea nemoralis in gardens and areas such as the Aldersbrook Exchange Lands. A very uncommon snail was found in 2024 between Aldersbrook Exchange Lands and Wanstead Park - a Roman Snail Helix pomatia. These are usually associated with chalky areas, and this area certainly isn't that. It is more usual to find just the shells, but this one - although not exactly kicking - was quite alive.

Slugs will be familiar to most people from their gardens, and perhaps the most recognisable of these will be the Arion species, either A. ater ater the Large Black Slug, or its variety A. ater rufus the Large Red Slug, which is far less common in this area. There will be other species easily found, but I don't profess to be knowledgable about these. One distinctive species I have been seeing is the Leopard Slug - or Great Grey Slug - Limax maximus, and more recently an invasive species known as the Three-band Garden Slug, which I believe to be Lehmannia valentiana.

Pond-living molluscs are particularly under-represented in this list, many were identified by Derek Mckewan after a pond-dipping exercise during a Wren Group "bio-blitz" on 5th October 2014. After the installation of a new pond in my garden, two species of snail spontaneously arrived: the Common Bladder Snail Physa fontinalis and the Wandering Snail Lymnaea peregra. The Swan Mussel Anodonta cygnaea has for long been known from the Ornamental Waters in the form of shells of dead animals, but during a period when the waters of the Heronry Pond became very low in 2009, live specimens were found.

Apart from a couple of garden worms, Annelid Worms have only been investigated during a pond-dipping exercise carried out under the leadership of Derek McKewan by the Wren Group. He identified three species of the Family Hirudinea - the freshwater leeches - from Perch Pond, Wanstead Park on 5th October 2014.

As for Crustaceans, an American Signal Crayfish Pacifastacus leniusculus was found by Heronry Pond in August 2001, and more have been seen since. In August 2004, a number of dismembered crayfish were found in rough grass just to the east of Alexandra Lake on Wanstead Flats. Is it possible that these had been taken from the lake by predators - perhaps gulls? In 2008, a representative from the angling club that fishes the Basin in Wanstead Golf Course reported that over 50,000 (!) had been caught there over the last few years. Chinese Mitten Crab Eriocheir sinensis have been reported from the River Roding as far north as Redbridge roundabout. The local Guardian Series Newspapers on 23rd October 2008 reported that the Environment Agency had found these crabs at Wanstead and further north. The freshwater shrimp Gammarus lacustris, and a water slater Asellus sp. was found in Perch Pond, Wanstead Park during a bio-blitz exercise and identified by Derek McKewan. The common Water Slater Asellus aquaticus is found in my garden pond. Land-based crustaceans are perhaps more familiar and finds so far are the Common Pill Bug Armadillidium vulgare, the Common Shiny Woodlouse Oniscus asellus, which was found in Wanstead Park, the Common Striped Woodlouse Philoscia muscorum, and the Common Rough Woodlouse Porcellio scaber, both present in my garden in Capel Road.

The species are listed in alphabetical Family order, within which the species is alphabetical.

In addition the following species have been reported, although not personally seen:

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