Udotea

Lore & Background

Udotea species are multinucleated green macroalgae found in tropical regions. Their thalli consist of an uncalcified rhizoid anchoring to substrates such as rock, sand, or mud; an uncalcified upright stalk (stipe) with a cortex; and a fan-shaped calcified blade. The stalk is composed of siphons positioned lengthwise, with lateral appendages forming the cortex. Blade siphons may be simple or complex, and siphon morphology depends on thallus location and life-history stage.

Reader's Guide

Udotea plays a role in sediment dynamics and reef building: upon death, its calcified thalli contribute sand and organic compounds, improving sediment as it decomposes. It also co-inhabits with other Udoteaceae macroalgae, providing refuge, food, and calcium carbonate. The genus produces bioactive compounds, including diterpenes such as udoteal (a deterrent against the herbivorous fish Eupomacentrus leucostictus) and udoteal B (antibiotic activity, limiting cell division in sea urchin eggs and harmful to damselfish). Other compounds isolated include lectins, petiodial, and udoteafuran, with antimicrobial, antiviral, anticoagulant, and antitumor potential. Sulfated polysaccharide-rich extracts from Udotea flabellum (sulfated homogalactans F-I and F-II) show anticoagulant and anti-proliferative properties. Udotea is not currently cultivated for aquaculture.

Did You Know?

• Udotea thalli have three parts: an uncalcified rhizoid, an uncalcified stalk with cortex, and a fan-shaped calcified blade.
• In the Western Atlantic, 21 Udotea species were noted in 1990, and 23 infrageneric taxa were identified in 2017.
• Male Udotea plants turn green and females grey in thallus color during reproduction.
• Udotea produces the diterpene udoteal, which deters the herbivorous fish Eupomacentrus leucostictus.