Bivalves · Marine Life

Brown mussel (Perna perna)

Eroded and less eroded brown mussels in a bed. Old Woman's River, Eastern Cape (2018). Shell smooth and yellow-brown, sometimes tinged with green or with a chevron pattern. Specimens from crowded intertidal beds often very elongated and almost rectangular in cross-section. Submerged, fast-growing specimens are taller and narrower. Up to 125 mm. The dominant mussel… Continue reading Brown mussel (Perna perna)

Barnacles · Marine Life

Grey volcano barnacle (Tetraclita serrata)

Close-up of a grey volcano barnacle. Mouille Point, Cape Town, Western Cape (2020) - iNaturalist Tall, dark-grey and volcano-shaped, with only four strongly-ribbed shell plates, the edges of which are difficult to distinguish. About 20 mm. One of the dominant invertebrates in the mid-intertidal zone of moderately sheltered shores. Two Oceans: A Guide to the… Continue reading Grey volcano barnacle (Tetraclita serrata)

Anemones · Cnidarians · Marine Life · South Africa

Crevice anemone (Anthopleura michaelseni)

Details of the spherules, and the long tentacles of the crevice anemone. Fishhoek, Western Cape (2020) - iNaturalist Also called long-tentacled anemone. Column with large sticky pads, to which shells and gravel adhere. Dark stripes usually radiate from mouth to the 96 long pink-to-brownish tentacles. Spherules present. Up to 150 mm in diameter, but commonly… Continue reading Crevice anemone (Anthopleura michaelseni)

Algae · Brown algae · Encrusting algae · Marine Life · South Africa

Ralfsia (Ralfsia verrucosa)

Details of the concentric rings of Ralfsia, with some missing patches (probably grazed). Cape Agulhas, Western Cape (2020). Ralfsia verrucosa can be considered an inactive taxon by some (for example, on iNaturalist). It is then replaced by Pseudoralfsia verrucosa. Forms flat patches or irregular, concentric rings. Brown, grading to khaki, with pale edges. About 1… Continue reading Ralfsia (Ralfsia verrucosa)

Echinoderms · Marine Life · Starfish

Reticulated starfish (Henricia ornata)

A maroon reticulated starfish found in a rock pool on the shore. Port Alfred, Eastern Cape (2023) - iNaturalist Arms long, very gradually tapering and cylindrical. Color orange to maroon with an irregularly-honeycombed surface texture. Up to 90 mm across. Thought to feed on sponges by everting the stomach and digesting the sponge tissue in… Continue reading Reticulated starfish (Henricia ornata)

Gastropods · Marine Life · Whelks

Scaly dogwhelk (Nucella squamosa)

Details of the operculum and the foot of the scaly dogwhelk. Unknown location, South Africa (2021). About 15 spiral ridges overlies longitudinal ridges, giving the shell a scaly (squamous) appearance.Operculum horny, brown-orange. Foot light orange, speckled white. About 35 mm. Occurs low on the shore or subtidally. Lays egg capsules resembling flat clubs. Shell usually… Continue reading Scaly dogwhelk (Nucella squamosa)

Algae · Brown algae · Marine Life

Dead-man’s finger (Splachnidium rugosum)

Wrinkling dead-man's fingers in a rock crevice. Hondeklipbaai, Northern Cape (2020) - iNaturalist Swollen yellow-brown, finger-like bladders, filled with thick, clear slimy mucilage, turgid when wet and becoming withered and wrinkled when dry. The main stipe is swollen with many similarly shaped side branches which are constricted at their point of origin and rounded at… Continue reading Dead-man’s finger (Splachnidium rugosum)

Algae · Encrusting algae · Marine Life · Red algae

Coralline crust (Spongites spp)

Cochlear coralline crust covering a rock surface. Jacobsbaai, Western Cape (2020) - iNaturalist Cochlear coralline crust (Spongites yendoi) Hard, encrusting species of crustose coralline algae (Rhodophyta). Thallus relatively thin, mainly composed of filaments of small, often fused, squarish cells, with the lowermost layer up to eight filaments thick of mostly elongated cells. Chalky-white in color,… Continue reading Coralline crust (Spongites spp)

Marine Life · Sedentaria · Worms

Cape reef-worm (Gunnarea gaimardi)

Cape reef-worm stuck in a rock crevice. Yzerfontein, Western Cape (2020). Previously known as Gunnarea capensis. Gregarious, forming massive intertidal reefs of sandy tubes. There is a double row of 40-50 stiff golden bristles on the head, forming a 'door' (operculum) that blocks the tube when the worm withdraws. Worms are about 50 mm long.… Continue reading Cape reef-worm (Gunnarea gaimardi)

Bivalves · Marine Life · South Africa

Mediterranean mussel (Mytilus galloprovincialis)

Mediterranean mussel bed surrounded by algae of all sorts. Yzerfontein, Western Cape (2020). Shell smooth, typically black or blue, shading to brown on the lower surface, but rarely light brown. Broad in cross-section and usually widest at base. Distinguished from Choromytilus meridionalis by pits in the resilial ridge. Up to 140 mm. Thought to be… Continue reading Mediterranean mussel (Mytilus galloprovincialis)