Pelagic Species Washed Ashore on the Cape Whale Coast

Many pelagic species (open ocean) are washed ashore and found in the intertidal zones on almost every walk. Colouration of these animals is the first clue to their normal habitat—either blue, silver, clear or counter-shaded, because there is nowhere to hide in the surface waters of the open ocean.

📷 Root-mouthed jellyfish with parasitic amphipods

Root-Mouthed Jellyfish (Eupilema inexpectata)

Often found washed ashore upside down. Although able to swim by pulsing water from their bells, onshore winds and currents overwhelm them. All jellyfish are carnivores stunning prey with stinging cells on their tentacles, but the Root-mouth lacks tentacles and feeds by filtering tiny prey through pores in the manubrium. Jellyfish are an important food for turtles and are even eaten by Great White Sharks. The small brown flecks seen in the photo are parasitic Amphipods (Hyperia galba) living inside the jellyfish umbrella.

By-the-Wind Sailor (Velella velella)

Comprises an oval float carrying a kinked vertical sail. The mouth is located underneath surrounded by simple tentacles with stinging cells (harmless to humans) used to capture plankton. This hydrozoan floats on surface water tension driven by prevailing winds.

Bluebottle / Portuguese Man-of-War (Physalia physalis)

Its venomous tentacles deliver a powerful sting to paralyze small fish. The bluebottle is not a single creature, but a colonial organism made up of minute specialized individuals called zooids. Loggerhead turtles are immune to the sting, as is the sea swallow.

Bubble-Raft Shell (Janthina janthina)

This thin, fragile violet snail has no operculum in the adult stage; it secretes mucus-coated bubbles from its foot to float upside-down on the ocean surface, where it feeds upon pelagic hydrozoans like the By-the-wind sailor and bluebottle.

Sea Swallow (Glaucus atlanticus)

A small (up to 3 cm) blue pelagic nudibranch that floats upside down on its back with the aid of a gas sac in its stomach. Counter-shaded in silver and dark blue, this ferocious predator eats bluebottles, storing their stinging nematocysts for its own defence to produce an even more powerful sting!

Blue Button (Porpita porpita)

Floats on a gas-filled disc surrounded by a skirt of short tentacles with mild stinging cells that have no effect on humans.

Columbus Crab (Planes minutus)

First noted by Christopher Columbus on his voyage to the West Indies, this pelagic crab inhabits floating weed rafts and the shells of Loggerhead turtles, hunting off its host and returning before the turtle swims away.

Yellow-Rimmed Goose Barnacle & Buoy Barnacle

Lepas anatifera: Attached to floating driftwood by a fleshy stalk. Dosima fascicularis: The only barnacle that produces its own polystyrene-like float from modified cement glands.