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Acar squamosa

This ark shell is usually found firmly attached to the underside of rocks subtidally, often in groups. It is much wider than it is high, and is whitish to light brown in colour with no significant markings. However, it is heavily sculptured, with radial and concentric lines that intersect and provide a grid like appearance. This roughly sculptured shell helps to distinguish it from other similar species, particularly Barbatia pistachia, which also has a grid-like sculpture, but much finer.

Monk Creeper

Plesiotrochus monachus

Ranging from pale, to brown and orange, the shell of this tall spired snail has convex, angular whorls, which are almost triangular, with distinct undulations. The pattern can vary, from tan spiral lines along the length of the shell, to dashed spiral lines at irregular intervals, and even no markings at all. The strong angular whorls help to distinguish this species from the many similar snails found in SA.

Tassled Crab

Pilumnus fissifrons

Pilumnus fissifrons is a small tan to brown crab that is common in rocky areas. Its body and legs are covered in fine, stiff hairs, and it has three large but blunt spines on the carapace behind the eyes. It is virtually indistinguishable from other pilumnid crabs found in SA, except for the presence of several clumps of long, erect and club-shaped hairs (or setae) on the top of the carapace and between the eyes. These features actually make it one of the easier species to identify from this notoriously difficult genus.

Ulva taeniata

directions_boat Introduced species

This bright green "sea lettuce" is native to the US Pacific coast, but is now commonly found in SA, usually on rocky platforms in moderate to rough conditions. Compared to the better known Ulva lactuca, its thin blades are narrower, around 2-5 cm wide. The blades branch towards the base of the plant and are usually ruffled or twisted.

Burchard's Dog Whelk

Tritia burchardi

This snail can be found in estuaries and lagoons intertidally. It is relatively bulbous and is distinctly ribbed. On the body whorl, the ribbing fades and the dorsal surface is smooth and unsculptured. The shell is a light green to brown, with darker brown colouration between the ribs. This species is native to Australia, but has established in some areas of New Zealand.

Scintillula solida

This tiny bivalve is a brilliant white in colour and globular. It has a smooth and shiny appearance with a very fine concentric sculpture. It can be difficult to distinguish from other galeommatid bivalves, including Lasaea australis, but its lack of purple pigmentation and less obvious sculpture can differentiate it from that species.

Ascidiella aspersa

directions_boat Introduced species

This introduced solitary ascidian is native to Europe, but now spread globally due to shipping. Its test is a cloudy white or grey, flecked with red and covered in white papillae. The relatively short siphons are lobed and can have red stripes inside. This species resembles many others in the Ascidia genus, but in those species there are usually no papillae.

Diala suturalis

This tiny snail can often be found in very shallow tidepools, where it feeds on filamentous algae. It has a moderately tall spire, with slightly convex whorls. The pattern is somewhat variable, but consists of spiral brown bands of varying width, the lines sometimes broken. The aperture is thin and straight-edged, unbroken by a siphonal canal. This species is difficult to differentiate from other small snails and expert examination can be helpful.

Stereotheca elongata

This pinnate (feather-shaped) hydroid colony can be found on seagrasses and algae, often Amphibolis stems. The colonies themselves can be encrusted by coralline red algae and other epiphytes. The terminal branches of the colony emerge from the zigzag main branches in an alternating arrangement on each side of the branch and the polyps emerge directly from these terminal branches, protected by their cup-shaped hydrothecae. This species can be difficult to identify, but has distinctive jagged-edged hydrothecae along with the other characteristics discussed here.

Leptochiton liratus

This uncommon chiton is a uniform light brown in colour. It has thin longitudinal grooves on both the pleural and lateral areas, although they are thickened or warped in places. It has a girdle of tiny scales, with a fringe of hair-like spicules. This species can be distinguished from other similar species by its uniformly thin sculpturing.