Burrowing anemone

Abstract: Brooding is known for at least 57 species within Actiniaria, making it a rare phenomenon among the approximately 1100 described species in the order. Within the order, brooders are known from taxonomically disparate groups in both suborders (Anenthemonae and Enthemonae) and all superfamilies except for Actinernoidea. Two-thirds of brooders do so internally and have a pan-latitudinal distribution whereas external brooders show a disproportionate diversity in the poles, particularly in the Southern Ocean. Here, we describe Halcampulactidae fam. nov., a new family of burrowing sea anemones from Antarctica characterized by a novel combination of morphological features: twelve mesenteries (eight macrocnemes and four microcnemes) and invaginations of the oral disc similar to glandular sacs of Oractiidae Riemann-Zurneck (Polar Biol 23:604–608, 2000) hypothesized to brood offspring. Halcampulactidae fam. nov. is the first endemic family from Antarctica and Halcampulactis solimar sp. nov. is the 11th species of sea anemone with parental care recorded from Antarctica; it is also the first burrowing anemone with external brooding from the Southern Ocean, representing the second instance of external brooding on the oral disc within the order Actiniaria. In addition, we use molecular evidence to establish the phylogenetic position of the new family within the order; Halcampulactidae fam. nov. is the first burrowing family within the superfamily Actinostoloidea. We discuss the evolution of external brooding within the superfamily in light of these new findings.

Abstract: Juveniles of the burrowing anemone Peachia parasitica, living on the scyphozoan Cyanea capillata, were obtained from Virginia, thus extending the southern limit for this species. Anemones were easily maintained in the laboratory; one lived for over four years. The feeding behavior is described.

Abstract: The maximum population density of the burrowing anemone (Ceriantheopsis americanus) was estimated at 17–28 animals m−2 in soft-bottom sediments of mid Narragansett Bay. The gut contents of the anemone indicated primary prey of harpacticoid and calanoid copepods. The consumption of calanoid copepods was higher in October than April, which may be due to decreased density of hapacticoids in the fall. The anemones apparently avoid fish predation in late summer by withdrawing into the sediments. After the seasonal fall migration of fish out of the bay, anemones reappear.

Abstract: Edwardsia migottoi sp. nov., a new species of burrowing anemone from the Southeast coast of Brazil, is described. It is also the first species of the genus reported from the Southwestern Atlantic. It is characterized by a rusty brown deciduous periderm, eight longitudinal rows of tubercles with nemathybomes, and nemathybomes with two types of nematocysts (pterotrichs and microbasic t-mastigophores). Edwardsia migottoi sp. nov. differs from other members of the genus by its number of tentacles, arrangement and cnida content of nemathybomes, musculature, and geographic distribution. The new species is the second member of the family Edwardsiidae Andres 1881 and the third species of burrowing sea anemone recorded from Brazil. The description of the new species lead to the recognition that the mesenterial morphology of the monotypic Pacific genus Metedwardsia Carlgren 1947 is unlike that of members of Edwardsiidae to which it belonged and similar to that of Halcampidae Andres 1883, resulting in its transfer to the latter family.