Chiridota heheva—the cosmopolitan holothurian

Abstract

Chemosynthetic ecosystems have long been acknowledged as key areas of enrichment for deep-sea life, supporting hundreds of endemic species. Echinoderms are among the most common taxa inhabiting the periphery of chemosynthetic environments, and of these, chiridotid holothurians are often the most frequently observed. Yet, published records of chiridotids in these habitats are often noted only as supplemental information to larger ecological studies and several remain taxonomically unverified. This study therefore aimed to collate and review all known records attributed to Chiridota Eschscholtz, 1829, and to conduct the first phylogenetic analysis into the relationship of these chiridotid holothurians across global chemosynthetic habitats. We show that Chiridota heheva Pawson & Vance, 2004 is a globally widespread, cosmopolitan holothurian that occupies all three types of deep-sea chemosynthetic ecosystem—hydrothermal vents, cold seeps and organic falls—as an organic-enrichment opportunist. Furthermore, we hypothesise that C. heheva may be synonymous with another vent-endemic chiridotid, Chiridota hydrothermica Smirnov et al., 2000, owing to the strong morphological, ecological and biogeographical parallels between the two species, and predict that any chiridotid holothurians subsequently discovered at global reducing environments will belong to this novel species complex. This study highlights the importance of understudied, peripheral taxa, such as holothurians, to provide insights to biogeography, connectivity and speciation at insular deep-sea habitats.

Cosmopolitan abyssal lineages? A systematic study of East Pacific deep-sea squat lobsters (Decapoda: Galatheoidea: Munidopsidae)

“…This fact together with the shallow divergence between this species and M. alvisca could indicate the existence of a single, widely distributed taxon in which hydrothermal vents could facilitate a type of stepping-stone dispersal. Cosmopolitanism is known for many deep-sea invertebrate species, for example nematodes at both genus-and species-level (Miljutin et al 2010;Zeppilli et al 2011), echinoderms (Thomas et al 2020) and molluscs (Oliver 2015), among others. The abyss has often been perceived as a homogenous habitat lacking horizontal barriers to dispersal (e.g.…”

Distribution of Megabenthic Communities Under Contrasting Settings in Deep-Sea Cold Seeps Near Northwest Atlantic Canyons

“…Most of them were mobile (e.g., decapods, sea spiders, echinoids, ophiuroids, and holothurians) and apparently do not have equally strong affiliations with a specific type of substrate as seen at BC (e.g., Polymastia and Hormathia). The holothurian Chiridota heheva seen at NC is a cosmopolitan chemosynthetic ecosystem species (Thomas et al, 2020) feeding on various food sources (Carney, 2010). Pantopoda and Lithodes crabs in chemosynthetic environments (e.g., Lithodes longispina) have been characterized as predators/scavengers (Bowden et al, 2013;Wang et al, 2016;Dietz et al, 2018) moving across habitats and searching for prey.…”

The genome of an apodid holothuroid (Chiridota heheva) provides insights into its adaptation to deep-sea reducing environment

“…Echinoderms are a rare component of deep-sea chemosynthetic ecosystems (Tunnicliffe, 1992). Chiridota heheva Pawson & Vance, 2004 (Apodida: Chiridotidae) is one of the few echinoderms that occupies all three types of chemosynthetic ecosystems (hydrothermal vent, cold seep, and whale fall) (Thomas et al, 2020). This suggests that the species is well adapted to deep-sea reducing environments.…”

“…Chiridota heheva derives nutrients from a variety of sources, extracting organic components from sediment detritus, suspended material, and wood fragments when available (Carney, 2010; Pawson & Vance, 2004). A peltate-digitate tentacle structure allows C. heheva to exploit various food sources by switching between deposit and suspension feeding (Thomas et al, 2020). The cosmopolitan distribution and special lifestyle of C. heheva make it an ideal model to study adaptation to deep-sea reducing environments in nonsymbiotic animals.…”