Antennella secundaria - Marine Life Encyclopedia

Antennella secundaria (Gmelin, 1791)

Antennella secundaria

Description: This is a tiny hydroid consisting of clusters of unbranched stems bearing hydrothecae in a line on one side of each stem. The stems are typically greenish-yellow in colour. Hydrothecae are well-separated on the stems, with a jointed section between each hydrotheca-bearing one. Typically 30mm in height, but white colonies larger than the normal form were found at Lundy Island in 1984 in abundance.

Habitat: Normally grows on bedrock, boulders or cobbles with some nearby sand or gravel causing scouring of the substratum. Usually in weak tidal streams.

Distribution: Widely distributed in the British Isles, but more common in the south.

Similar Species: The overall appearance of this species is similar to that of individual side-branches of Halopteris catharina but this species has unbranched stems arising from a basal rhizoid mass.

Key Identification Features:

Hairlike colonies with hydrothecae arranged in a single series

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

WoRMS: Species record : World Register of Marine Species.

iNaturalist: Species account : iNaturalist World Species Observations database

Picton, B.E. & Morrow, C.C. (2016). Antennella secundaria (Gmelin, 1791). [In] Encyclopedia of Marine Life of Britain and Ireland.
https://www.habitas.org.uk/marinelife/species.asp?item=D5720 Accessed on 2025-05-20

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