Mermaid's Wine Glass

Overview

Acetabularia acetabulum, commonly known as the "mermaid's wine glass," is a unique species of green alga endemic to the Mediterranean Sea. Despite its complex, plant-like appearance, the entire organism consists of a single, giant cell, making it a significant subject for biological research.

Appearance

This alga is easily recognized by its distinct, parasol-like shape. It features a slender, vertical stalk that can reach up to 5 cm in height, topped with a delicate, disc-shaped cap measuring 5 to 12 mm in diameter. The cap is typically pale green, bluish-green, or whitish, and is marked by fine, radial striations. The base of the stalk is anchored to hard substrates by root-like structures called rhizoids.

Biology & behavior

The mermaid's wine glass is highly seasonal and is generally only visible during late spring and summer. During the autumn and winter months, the visible portion of the alga disappears, leaving only the basal rhizoids attached to the substrate. Because it is a single-celled organism, its entire life cycle—including the development of its reproductive structures—is contained within this one cell. The nucleus is located near the base, close to the rhizoids.

Distribution & habitat

This species is primarily found in the Mediterranean Sea, though it has also been reported along the southern coasts of Spain and the Canary Islands. It thrives in shallow, well-lit, and calm waters, typically at depths of 2 to 5 meters. It prefers to colonize solid, rocky surfaces, including rocks, shells, and other hard debris, often forming small, lawn-like patches in sunny, sheltered areas.