チリメンヒラムシ

Overview

Paraplanocera oligoglena is a widely distributed polyclad flatworm often found in littoral and sublittoral zones. It is frequently encountered by snorkelers and tide-pool observers, making it one of the more conspicuous species in its range.

Distribution & habitat

This species has a global distribution and is commonly found in intertidal pools, on reefs, and across lava benches. It typically resides under rocks in areas characterized by moderate to heavy wave action, often associated with encrusting bryozoans, green seaweed, and chitons.

Appearance

These flatworms are ovate to circular in shape with a highly ruffled, crenulated margin. While smaller individuals are translucent and buff-colored, they become more densely pigmented as they grow, often developing a mottled or reticulated dark brown pattern. The margin is typically white, interrupted by brown markings. A key identifying feature is the presence of distinct head tentacles, which are striped in cream and brown and ringed by numerous eyes at their base.

Feeding

Paraplanocera oligoglena is a predatory species. Research indicates it feeds on various gastropods, including sea snails and sea hares. Its complex feeding process involves distinct stages of prey recognition, stalking, capture, and ingestion. Internally, it utilizes an intricately branched digestive system with bidirectional gastrovascular flow to process nutrients.