Maiden's Hair Algae

Chlorodesmis fastigiata

Also known as Maidens Hair, Turtle Weed, Green Hair Plant

SaltwaterMacroalgaeCuttings

Maiden's Hair Algae (Chlorodesmis fastigiata) — Dr. Robert Ricker, NOAA/NOS/ORR · Public domain

Care at a glance

Light: High light
CO2: No CO₂ needed
Growth rate: Medium
Placement: Epiphyte
Type: Macroalgae
Temperature: 73–81°F (23–27°C)
pH: 8.0–8.4
Max height: 3.1 in (8 cm)
Spread: 5.9 in (15 cm)
Nutrient uptake: Water column
Growth region: Submersed
Difficulty: Medium
Origin: Tropical Indo-Pacific reefs, including Palau, Guam, and the Great Barrier Reef
Family: Udoteaceae

Overview

Maiden's Hair is grown as a lush ornamental turf macroalga that also takes up nitrate and phosphate from the water column. It wants strong light and notably high flow, more current than most refugium macroalgae, to keep its fine filaments clean and healthy. It attaches to rock or rubble as a low epiphytic tuft rather than rooting in sand, and while it is reef safe it can spread if conditions suit it, so many keepers site it in a refugium or on a dedicated rock rather than loose in a mixed reef. It is a medium-difficulty alga: undemanding to feed but fussy about getting enough flow and light, and its chemical defenses mean cleanup crews will not keep it trimmed for you.

In the wild

A vivid green macroalga of shallow tropical Indo-Pacific reefs, growing as dense turf-like clumps of fine, forking filaments that resemble soft grass or hair. It anchors to rock and coral rubble in bright, high-flow reef zones from the surface down to around 60 meters, forming compact tufts across the reef surface.

Good to know

Chlorodesmis fastigiata is built from coenocytic siphonous filaments that fork dichotomously into fine hair-like segments. It produces chlorodesmin, a diterpenoid feeding-deterrent that makes it unpalatable to most reef herbivores, so it is often left untouched even in heavily grazed reef zones. It has a documented symbiotic relationship with certain guard crabs that shelter in its tufts and defend it, and unlike Caulerpa it is a non-Caulerpa siphonous green not prone to the same holocarpic crash.

Did you know

Maiden's Hair algae hosts guard crabs that live in its filaments and nip at nearby corals and grazers, an unusual partnership where the alga's chemical defenses and its live bodyguards together keep it from being eaten.