Solitary Pink-Mouth Hydroid (Ectopleura marina)

Description: These flower like hydroids consist of gray stem like features called pedicels with pink-orange tentacles atop the end of the stem. These pink tentacles are arranged in two rings: an inner ring of oral tentacles and larger outer ring of feeding tentacles used to snag prey. Although hydroids are normally known to cluster together, these solitary pink-mouth hydroids live their individual lives out separately from each-other or in well spaced out clusters.

Habitat: This species ranges from British Columbia to California. They live in spaced out clumps attached to rocks, floats, and other hard surfaces. They inhabit low intertidal and sub-tidal zones due to the fast-flowing current and exposed rocky shores.

Diet: These hydroids stun their prey with their tentacles, and usually eat copepods, marine worms and small crustaceans.

Reproduction: Male polyps release sperm into the water to fertilize the female polyps that hold on to the eggs. Once fertilized and developed into larvae, the larvae are released to settle elsewhere.

Tide Pool Tidbits:

• Solitary pink-mouth hydroids are typically 2-5 cm tall with 18 tentacles.

• They belong to one of the most diverse groups of multicellular organisms.

• Not many things eat solitary pink-mouth hydroids due to their stinging tentacles, but it is the meal of choice for the thick-horned nudibranch.

Reference: Washington State Department of Ecology