Giant Green Anemone (Anthopleura xanthogrammica)

Description: This species of anemone can grow to be as large as a dinner plate, or about 25 centimeters in diameter and 30 centimeters tall. As the name suggests, this species of anemone is a lovely green color, and its column or base is an olive green. The flat surface called the oral disc and its surrounding tentacles can vary in their shades of green, from a vibrant bright green to a more blue hue and sometimes a grayish-blue color; the tentacles can also sometimes be a bit whiter. Some of their green color can be attributed to symbiotic dinoflagellates and algae that live within the anemone.

Habitat: The giant green anemone’s geographic distribution ranges from Alaska to Baja California along the Pacific Coast of North America.

Diet: The diet of this species typically includes small fish, crabs, and mussels that have detached from rocks.

Reproduction: Giant Green Anemones reproduce sexually through broadcast spawning - males and females release gametes into the water for external fertilization. This is typically triggered by warming waters at the end of summer, start of fall.

Tide Pool Tidbits:

• Similar to the aggregating anemone, the giant green anemone has symbiotic dinoflagellates and algae living within its tissues. However, unlike the aggregating anemone, the giant green anemone makes its green color itself along with the added color from the symbiotic algae, giving it the much more vibrant green color. In this relationship, the symbionts are protected from grazers and the anemone gains nutrients that result from photosynthesis. 

• On somewhat rare occasions, giant green anemones can be found eating much larger meals, such as different species of seabirds (typically their smaller young that have died and fallen into the water).

• Unlike the aggregating anemone, the giant green anemone avoids crowded spaces and prefers to live in solitude. Broadcast spawning helps them disperse their young instead of crowding around one area.

• The lifespan of giant green anemones is officially unknown. Some individuals have been known to live to be over 100 years old!

Reference: Animal Diversity Web