This organism was quite abundant and frequently seen on my quest for Pacific Ocean tidepool creatures.
Their green color comes from an endosymbiotic (living within the anemone mutually benefiting both organisms), photosynthetic algae in their tentacles and body.
The tentacles can be retracted inside the body cavity or expanded to catch passing prey. When not submerged in the water, they pretty much look like blobs covered with fragments of shells from things they’ve eaten.
Aggregating Anemones catch prey that comes within reach of their tentacles and immobilize it with the aid of their venom-filled stinging cells within their tentacles.
The tentacles are triggered by the slightest touch, firing a harpoon-like filament into their victim and injecting a paralyzing neurotoxin. The prey is then transported to the anemone’s mouth and engulfed.
Despite the potency of its venom to its prey, sea anemones are harmless to humans. I stuck my finger near this one and it wrapped around it, trying to pull my finger into its mouth!
The closest relatives of these amazing creatures are jellyfish and corals. This was a fun animal to make an acquaintance with on my trip to California.