Red-throated Ascidian

Overview

The red-throated ascidian (Herdmania momus) is a widely distributed, solitary sea squirt frequently encountered in tropical and subtropical marine environments. Often found as part of the cryptic fauna, these animals are known for their ability to colonize both natural reefs and artificial structures like jetties and floating docks.

Appearance

This species typically features an inflated, spherical body that can grow up to 18 cm in height. It is characterized by two short, trumpet-shaped siphons at the anterior end, which often display distinct longitudinal stripes. The body wall, or tunic, is translucent and ranges in color from peach to pink or red. Beneath the surface of the tunic and internal organs lie tiny, embedded calcareous spicules. While younger individuals possess a soft, thin, and transparent tunic, older specimens develop a thicker, more opaque, and leathery texture.

Distribution & habitat

Native to the Indo-Pacific and Red Sea, Herdmania momus has expanded its range significantly, including its establishment as an introduced species in the Mediterranean Sea via the Suez Canal. It is commonly found in shallow waters, often attached to the undersides of coral plates or smooth artificial substrates such as breakwaters and ship hulls.

Biology & behavior

As an opportunistic filter-feeder, this ascidian relies on a continuous secretion of a mucous-mesh to capture microscopic particles from the water column. This process is metabolically demanding, with the animal producing a high volume of mesh relative to its body mass daily. While it is a common inhabitant of reef ecosystems, its distribution can appear patchy, likely influenced by specific larval settlement cues.