The Hydroid and the medusaNeoturris pileata

Abstract

The hitherto unknown hydroid of the anthomedusa Neoturris pileata has been found abundantly in the Clyde Sea Area, and medusae from it have been reared. The hydroid and the stages of development of the medusa are described and figured. The medusa is commonly present in the plankton in this area.The identity of the hydroid Perigonimus abyssi, which closely resembles Neoturris pileata, is discussed: it cannot be determined certainly until medusae have been reared from the hydroid.The habitat and the distribution of the hydroid N. pileata are described and discussed. In the Clyde Sea Area it is found at depths from about 50 m to the greatest in the area (160-180 m) on the shells of living protobranch molluscs of the genus Nucula in soft mud-very abundantly on N. sulcata, commonly though less abundantly on N. turgida, very sparingly on N. nucleus, and very rarely on N. tenuis. It has not been found on Nuculana minuta nor on a variety of other animals examined. A comparative study has been made of the burrowing habits of these species of protobranchs, and correlations have been found between these habits and the varying degrees of hydroid settlement on the different species. Neoturris pileata has specialized habits adapted to the peculiar burrowing mode of life of these molluscs.The world distributions of the medusa N. pileata and the species of Nucula with which its hydroid has been found associated in the Clyde Sea Area are described and discussed, and correlations are shown.The seasonal occurrence of the medusa is described; and probable relations between its seasonal appearance in different places and the hydrographic and the climatic conditions there-particularly water-mixing and its effect on the temperature and the oxygen-content of the sea-are discussed. Kramp

Fauna of the Mediterranean Hydrozoa.

“…The outer, generally convex, surface is the exumbrellar surface (exumbrella); the inner concave surface is the subumbrellar surface (subumbrella), the concavity being the subumbrellar cavity. Edwards, 1965;D after Stokes, 1974;E after Russell, 1953). dac: dactylozooid; fsp: female sporosac; ga: gastrozooid; hca: hydrocaulus; hcl: hydrocladium; ht: hydrothecae; hth: hydranth; hyr: hydrorhiza; mb: medusa bud; msp: male sporosac; pe: pedicel; pht: pseudohydrotheca; she: shell; sp: fixed sporosac; tz: tentaculozooid.…”

On a collection of hydroids (Cnidaria, Hydrozoa, Hydroidolina) from the west coast of Sweden, with a checklist of species from the region

“…Current knowledge on taxonomy, nomenclature, life cycle, and seasonality of this species has been summarized by Schuchert (2007). He followed Edwards (1965) in recognizing L. abyssi, similar to L. octona but even more like Neoturris pileata (Forsskål, 1775), as valid pending more information on its life cycle. The three, with similar hydroids, are sympatric in southwestern Scandinavia.…”

“…Neoturris pileata. -Edwards, 1965: 461.-Rees & Rowe, 1969: 10.-Schuchert, 2007 14. Leuckartiara octona: part of colony with hydrocaulus, hydranths, and gonophores, ROMIZ B3931.…”

“…Other contributions to knowledge of hydroids from western Sweden exist in various faunal surveys (Lönnberg 1898(Lönnberg , 1899b(Lönnberg , 1903Michanek 1967;Lundin et al 2007Lundin et al , 2009, in accounts of one or two species (Lönnberg 1899a;Kramp 1935aKramp , 1941Hult 1941;, and in the classic studies on Gullmarfjord biocoenoses by Gislén (1930). Species from western Sweden are also mentioned in certain works dealing largely with hydroids from other areas (Winther 1880a;Fenchel 1905;Kramp 1935b;Edwards 1965Edwards , 1973aCornelius 1975bCornelius , 1979Cornelius , 1982Cornelius , 1990Cornelius , 1995aCornelius , b, 1998Cornelius & Ryland 1990;Marques et al 2000;and Schuchert 2004and Schuchert , 2008band Schuchert , 2010. Finally, studies on nematocysts and isozymes of campanulariid hydroids obtained in Swedish waters were undertaken by Östman (1979a, b, 1982a, b, 1983, 1987, 1999) and Östman et al (1987, 1995).…”

Hydroidomedusae (Cnidaria: Hydrozoa) symbiotic radiation

“…(Edwards, 1965), Hydractinia angusta is associated with Adamussium colbecki (Cerrano et al, 2000(Cerrano et al, , 2001, the Zanclea costata colonies live on Chamelea gallina, Cardium sp. Neoturris pileata produces a dense layer on the anterior and ventral edge of the shells of the bivalve Nucula spp.…”