Pteraster tesselatus
Slime star emits toxic mucus to evade predators.
The slime star, also called the cushion star, is a starfish from the North Pacific. It has a wide central disc and five short, blunt arms with tips that curve upward, reaching about 15 cm across. Its upper surface looks puffy because it is covered by a thick, raised, fleshy membrane that is smooth and soft. This membrane can be pale brown, grey, red, or orange, often marked with a darker, symmetrical pattern. It hides the madreporite and the scales underneath, with a spongy tissue filling the gap. A central pore in the membrane lets water move through. Each arm has rows of fan-shaped groups of five to seven spines, with two rows of tube feet between them. At the tip of each arm, a red eyespot is surrounded by spines.
This starfish lives in rocky areas along the west coast of North America, from the Bering Sea south to central California, at depths up to 950 m. It is also found near the Aleutian Islands and Japan, usually in places with strong currents.
It eats various bottom-dwelling invertebrates, such as the breadcrumb sponge, the false jingle shell, other scallops and clams, and colonial sea squirts like *Aplidium* and *Didemnum* species. It also feeds on the bacterial film that grows on mussel surfaces. When attacked by predators like the morning sun star or the sunflower star, it releases large amounts of repellent mucus, which often lets it escape. This mucus is toxic and can kill other invertebrates that get immersed in it.
Breeding happens in summer. A female releases a small number of eggs into the water, and nearby males release sperm. The fertilized eggs, bright orange or yellow and wrapped in a gelatinous membrane, rise to the surface. They become planktonic and go through several developmental stages over about 25 days, then metamorphose into juvenile starfish and settle on the seabed. Several different species of polychaete worms often live symbiotically in the grooves on the starfish’s underside.
Quick Facts
- Genus
- Pteraster
- Species
- tesselatus
Facts from the source article.
Lore & Background
The slime star has a wide central disc and five stumpy arms with upturned tips. Its entire aboral surface is covered by a thick, raised, fleshy membrane with a smooth soft texture, colored pale brown, grey, red, or orange, often with a symmetrical darker pattern. This membrane conceals the madreporite and scales, and a central pore allows water movement. The arms have rows of fan-shaped groups of five to seven spines between which are two rows of tube feet, and a red eyespot surrounded by spines at the apex of each arm.
It occurs in rocky areas, usually where the current is strong, and feeds on various benthic invertebrates including the breadcrumb sponge, false jingle shell, other scallops and clams, colonial sea squirts, and bacterial film on mussels. When attacked by predators such as the morning sun star or sunflower star, it emits great quantities of repellent mucus that is toxic and can kill other invertebrates immersed in it.
Breeding occurs in summer: females release a small number of eggs into the water, males release sperm, and fertilized eggs rise to the surface. The eggs are bright orange or yellow, wrapped in a gelatinous membrane, and become planktonic for about 25 days before metamorphosing into juveniles and settling on the seabed. Polychaete worms often live symbiotically within its ambulacral grooves.
Reader's Guide
Pteraster tesselatus is significant for its unique defensive mechanism: it emits great quantities of repellent mucus when attacked by predators such as the morning sun star or sunflower star. This mucus is toxic and has been shown to kill other invertebrates immersed in it, allowing the slime star to often evade predation. Its inflated appearance, due to a thick fleshy membrane covering the aboral surface, is a distinctive morphological trait that conceals the madreporite and scales. The species also plays a role in its ecosystem as a predator of benthic invertebrates, including sponges, bivalves, and colonial sea squirts, and it feeds on bacterial films on mussels. Its breeding strategy involves a small number of eggs that become planktonic for about 25 days, with bright orange or yellow eggs wrapped in a gelatinous membrane. Additionally, it hosts symbiotic polychaete worms within its ambulacral grooves, indicating a complex ecological relationship. The slime star's range extends from the Bering Sea to central California and includes the Aleutian Islands and Japan, typically in strong currents at depths up to 950 meters.
Did You Know?
- The slime star emits toxic mucus that can kill other invertebrates immersed in it.
- Its aboral surface is covered by a thick, fleshy membrane that conceals the madreporite and scales.
More in Starfish, Part 3 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced