. The Canadian field-naturalist. 262 The Canadian Field-Naturalist Vol. 92. Figure 1. Nematostella vectensis from Minas Basin, Nova Scotia. Note the tentacle buds in addition to the 20 full-sized tentacles. the only anemone known to feed on insects. Minas Basin anemones fed on chironomid larvae and corixids, and Lindsay (1975) also reported them feeding on midge larvae. Ane- mones in Half-Moon Pond, Norfolk, England feed on the larvae of Chironomus salinarius and on harpacticoid copepods (Williams 1976). Insects, however, did not make up a sizeable portion of the anemones' diet in the Minas Ba
. The Canadian field-naturalist. 262 The Canadian Field-Naturalist Vol. 92. Figure 1. Nematostella vectensis from Minas Basin, Nova Scotia. Note the tentacle buds in addition to the 20 full-sized tentacles. the only anemone known to feed on insects. Minas Basin anemones fed on chironomid larvae and corixids, and Lindsay (1975) also reported them feeding on midge larvae. Ane- mones in Half-Moon Pond, Norfolk, England feed on the larvae of Chironomus salinarius and on harpacticoid copepods (Williams 1976). Insects, however, did not make up a sizeable portion of the anemones' diet in the Minas Basin, even though chironomids were especially abundant. The major prey were Hydrobia minuta and copepods (Table 1) which were also the most abundant animals in the pools. This is what one would expect for an animal that is basically sessile and opportunistic and that cannot actively pursue its prey. Anemones collected in 1972 and 1973 had not ingested numbers of chironomids and corixids comparable to the numbers taken in the earlier collections of anemones. This is not really sur- prising since chironomids and corixids are comparatively large active animals and when they came in contact with a tentacle they were usually observed to break away easily. Hydrobia are also large but they are relatively slow, and their reaction to attack may be simply to withdraw into their shell and thus give the anemone an opportunity to ingest them without any trouble. Anemones examined from 1965, 1966, and 1971 apparently did not ingest any of the smaller animals such as copepods. They are often difficult to distinguish in dissected anemones, however, and it is possible that these smaller food items were present but were overlooked. No explanation could be found for the anomalous anemones. Williams (1975) sug- gested three possibilities: imperfect asexual fission, regeneration of a damaged animal, or a genetic defect in the zygote. All of these possibilities are reasonable, but as yet, no evidence
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