Green Feather Alga

Overview

Green Feather Alga (Caulerpa sertularioides) is a delicate, light-to-yellowish green marine alga widely distributed across tropical and subtropical waters. It is characterized by its distinct, feather-like fronds that rise from creeping runners, often forming dense, carpet-like patches on the seafloor.

Appearance

This species features upright, flattened fronds that typically reach 3–5 cm in height. The fronds consist of a central midrib with oppositely attached, needle-shaped branchlets that are rounded and slightly curved. It grows from a horizontal creeping stolon, which is anchored to the substrate by fine rhizoids. It is often confused with the invasive Caulerpa taxifolia, but can be distinguished by its more delicate structure and rounded, rather than angular, branchlet tips.

Distribution & habitat

Caulerpa sertularioides is found globally in warm, quiet marine environments, including the Pacific, Indian, and Atlantic Oceans. It typically inhabits shallow reef flats, tide pools, and sandy bottoms, where it attaches to hard substrates or coral rubble. While it is indigenous to many regions, it has shown the capacity to spread aggressively in certain areas, sometimes overgrowing coral communities.

Biology & behavior

This alga is highly adaptable and can thrive in varying temperatures and nutrient conditions. It reproduces primarily through clonal propagation, where fragments of the stolon or fronds break off and establish new colonies, though it is also capable of sexual reproduction by releasing gametes into the water column. Its growth and photosynthesis rates may increase in warmer, high-CO2 environments, which has raised concerns regarding its potential as an invasive species in non-native regions.