Algae · Brown algae · Marine Life

Starred cushion (Iyengaria stellata)

Star cushion alga in a rock pool. Cape Agulhas, Western Cape (2020) - iNaturalist Plants yellow-brown, forming thin, globose cushions of compacted branching tubes, irregularly furrowed and convoluted. Surface covered with knobbly protuberances. Thalli at first solid but older plants becoming hollow in the center. Up to 10 cm in diameter and 3 to 4… Continue reading Starred cushion (Iyengaria stellata)

Barnacles · Marine Life

Toothed barnacle (Chthamalus dentatus)

Toothed barnacles on a rock face. Cape Agulhas, Western Cape (2020) - iNaturalist A small, flat, dirty-white barnacle with a membranous (not calcareous) base. The projecting, finger-like ridges on the six shell plates produce the characteristic star-shaped outline. Between 5 - 10 mm. Common in the upper intertidal, especially on the South and East coasts.… Continue reading Toothed barnacle (Chthamalus dentatus)

Marine Life · Sedentaria · Worms

Blue coral-worm (Pomatoleios kraussii)

Blue coral-worm reef. Port St Johns, Wild Coast, Eastern Cape (2021). Also known as Spirobranchus kraussii. Gregarious, building massive blue colonies of interwoven tubes which are calcareous (a feature of the family Serpulidae). Head with two rows of feathery branches and a stalked operculum that has two pointed 'wings' and a flat calcareous cap. Worms… Continue reading Blue coral-worm (Pomatoleios kraussii)

Limpets · Marine Life

Goat’s eye limpet (Cymbula oculus)

Goat's eye limpet with Ralfsia covering its shell and a little blurry isopod. Mosselbaai, Western Cape (2022). Shell flat, dull brown above, with above 10 major ribs that project from the margin. Interior with a broad black margin and a pink-brown center. Juveniles are yellow, with iridescent green flecks. About 100 mm. Lives in the… Continue reading Goat’s eye limpet (Cymbula oculus)

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)

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)

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)