Popular invertebrates (marine) View all »
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Giant clam (Tridacna gigas)
This enormous shellfish is the largest species of bivalve mollusc in the fossil record, and the heaviest of all the living molluscs. Like…
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Compass jellyfish (Chrysaora hysoscella)
The compass jellyfish has a saucer-shaped bell, with 32 semi-circular lobes around the fringe, each one with a brown spot. On the upper…
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Elkhorn coral (Acropora palmata)
Staghorn corals are among the fastest growing corals on reefs, and are excellent reef-builders. The name Acropora literally means a porous…
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Mushroom coral (Heliofungia actiniformis)
Rather than forming colonies like most other corals, this mushroom coral (Heliofungia actiniformis) is solitary and free-living; that is, it…
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Purple sea urchin (Strongylocentrotus purpuratus)
The purple sea urchin is an aptly named species, easily identified by the strikingly vivid, purple spines that project from its rounded body…
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Horseshoe crab (Limulus polyphemus)
The horseshoe crab (Limulus polyphemus) is a ‘living fossil’: forms almost identical to this species were present during the Triassic period…
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Flowerpot corals (Goniopora spp.)
The appearance of this pretty coral belies its aggressive behaviour. Many individual coral polyps, (anemone-like animals that secrete a…
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Common lobster (Homarus gammarus)
The common lobster (Homarus gammarus) is a very large and commercially important species. The upper surface is dark blue in colour with…
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Beadlet anemone (Actinia equina)
The beadlet anemone is the most familiar sea anemone in Britain. When disturbed or exposed to air at low tide it appears as a bright red…
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Cauliflower corals (Pocillopora spp.)
This hardy, widespread and common coral can easily be identified by the presence of wart-like growths, called verrucae, which cover the…
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Nautilus (Nautilus pompilius)
Information on this species is currently being researched and written and will appear here shortly.…
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Staghorn coral (Astreopora expansa)
One of the most distinctive species in its genus, the variably brown, pink or dark green colonies of Astreopora expansa take the form of…
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Common octopus (Octopus vulgaris)
The cephalopods (meaning ‘head-footed) are a group of molluscs that contain the octopuses, squid and cuttlefish, and are probably the most…
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Edible sea urchin (Echinus esculentus)
The edible or common sea urchin (Echinus esculentus) has a large, rounded 'shell', which is actually an external skeleton, correctly called…
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Native oyster (Ostrea edulis)
The native oyster is a bivalve mollusc, which means ‘two shells’, and is rough, scaly and yellowish-grey in colour. Each valve differs in…
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Lace coral (Stylaster californicus)
Lace corals form ornate tree-like structures, with all the fine, tapered branches growing in one plane. These delicate fan-like corals are…
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Sea lemon (Archidoris pseudoargus)
The sea lemon, Archidoris pseudoargus (also known as Archidoris tuberculata in much of Europe) is a common sea slug around Britain. It has…
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Velvet swimming crab (Necora puber)
The fast-moving velvet swimming crab has a flattened carapace, which is wider than it is long. The upper surface is blue but has a…
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Common cuttlefish (Sepia officinalis)
The cephalopods (meaning 'head-footed'), a group of molluscs containing the octopuses, squid and cuttlefish, are probably the most…
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Acorn barnacle (Semibalanus balanoides)
Barnacles are well-known intertidal organisms. They were not firmly accepted to be crustaceans until the 1830s; before this time, the…
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Common starfish (Asterias rubens)
The common starfish (Asterias rubens) has five arms (although individuals may occasionally have just four or as many as six). The colour of…
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Fire corals (Millepora spp.)
Fire corals get their common name from the painful stings they inflict on divers. Approximately 50 species of fire coral have been…
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Lugworm (Arenicola marina)
The presence of this lugworm can be detected by the characteristic signs of one of its U or J-shaped burrows; depressions are formed at the…
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Sea slater (Ligia oceanica)
The common sea slater is a sea-shore relative of woodlice that can grow up to 3 cm in length. It has a flattened, oval-shaped body that is…
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North Pacific giant octopus (Enteroctopus dofleini)
True to its name, the North Pacific giant octopus is the largest of all octopus species, and, along with other cephalopods (a group of…
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Cuban cave shrimp (Barbouria cubensis)
This is a brightly coloured shrimp with an arched body and rostrum. The colour of the shrimp varies from vivid red and orange to pale yellow…
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Common jellyfish (Aurelia aurita)
As its name suggests, the common jellyfish (Aurelia aurita) is the most common jellyfish species on British shores. The body is a saucer…
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Black abalone (Haliotis cracherodii)
The exterior of this marine gastropod mollusc’s shell varies in colour from dark blue through dark green to black. It is smooth with little…
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Elegance coral (Catalaphyllia jardinei)
With its distinctive green tentacles, tipped with bright pink, elegance coral (Catalaphyllia jardinei) is one of the most beautiful of…
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Humboldt squid (Dosidicus gigas)
Information on the humbolt squid is currently being researched and written and will appear here shortly.…
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Razor shell (Ensis ensis)
This razor shell (Ensis ensis) is a common, burrowing mollusc, which has an elongated fragile and narrow shell shaped like a cut-throat…
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Goose barnacle (Lepas anatifera)
Goose barnacles gave rise to one of the strangest of animal beliefs. The heart-shaped shell, or ‘capitulum’, is a chalky-white in colour and…
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Closed brain coral (Leptoria phrygia)
Forming large, irregular-shaped mounds covered by a dense, maze-like network of sinuous ridges and valleys, Leptoria phrygia is a striking…
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Common shore crab (Carcinus maenas)
As its name suggests, the common shore crab is one of the commonest crabs on the British shore, and anyone who has gone rock-pooling is…
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Southern blue ringed octopus (Hapalochlaena maculosa)
Information on the southern blue ringed octopus (Hapalochlaena maculosa) is currently being researched and written and will appear here…
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Tall sea pen (Funiculina quadrangularis)
Sea pens are colonial organisms that belong to the same group as corals and sea anemones. Each animal comprises of a colony of soft-bodied…
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Jewel anemone (Corynactis viridis)
The jewel anemone (Corynactis viridis) is so-called because of its spectacular colouration. Individuals may be bright green, orange, red…
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Flat periwinkle (Littorina obtusata)
Periwinkles are a large family of gastropod molluscs found on the shore. The flat periwinkle is so-called because the spire of the shell is…
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Black corals (Cirrhipathes spp.)
Also known as whip or wire corals, Cirrhipathes species are long, unbranched corals, which extend up to three metres or more, from a base…
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Common limpet (Patella vulgata)
The common limpet is a well-known seashore species. It has a conical shell, the outer surface of which is greyish-white. Shells situated…
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Ctenella coral (Ctenella chagius)
An ancient survivor from the Cretaceous period, Ctenella chagius is the only coral species of the family Meandrinidae found within the…
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Masked crab (Corystes cassivelaunus)
The masked crab (also known as the sand crab) has an elongated carapace, which is reddish brown to yellow in colour, and sometimes features…
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Pavona coral (Pavona cactus)
Pavona cactus is a scleractinian coral, meaning that it is a ‘hard’ coral with a limestone skeleton. It is pale brown or greenish-brown in…
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Sea-spider (Nymphon gracile)
The sea-spiders, or pycogonids, are an unusual group of marine arthropods, which are completely unrelated to terrestrial spiders, despite…
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Finger coral (Porites porites)
Porites corals form some of the largest of all coral colonies, with some reaching an incredible eight metres in height. The growth rate of…
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Common whelk (Buccinum undatum)
This large, common whelk has a stout, yellowish-brown shell with lighter and darker spiral areas. It has 7-8 whorls, and a large oval…
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Curled octopus (Eledone cirrhosa)
The cephalopods (meaning 'head-footed'), a group of molluscs that contain the octopuses, squid and cuttlefish, are probably the most…
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Common hermit crab (Pagurus bernhardus)
Despite the common name, hermit crabs are related more closely to lobsters than to crabs. They lack a hard carapace, and adopt the empty…
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Red coral (Corallium rubrum)
The beauty of Corallium corals may be their downfall, as they are harvested at unsustainable levels to be made into expensive jewellery or…
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Common cockle (Cerastoderma edule)
This well-known edible cockle has a solid shell, consisting of two valves, which feature prominent ribs and concentric growth-lines. The…

















































