Chemically regulated feeding by a midwater medusa

Abstract

Planktonic cnidarians are principal predators in the vast habitats between the ocean's surface and the deep‐sea floor. Almost nothing is known, however, about the chemical ecology of these fragile midwater animals because of difficulties associated with collecting healthy specimens and con‐ducting experiments in the field. With the use of a remotely operated vehicle, we found that the hydromedusa Mitrocoma cellularia is not a passive “drift‐net” predator. This relatively simple gelatinous organism reacted to both the taste and smell of prey in the laboratory and in situ. Our results comprise the first definitive demonstration that a species of pelagic cnidarian responds behaviorally to chemical signals, and they lend new insight into the role of chemoreception in structuring mid‐water communities.

Changes in diel diving patterns accompany shifts between northern foraging and southward migration in leatherback turtles

“…Assessing abundance of jellyfish through trawl sampling (e.g., Purcell et al 1999) is inherently difficult, as associated damage to these organisms makes counting them challenging (Graham et al 2003). However, acoustic (Purcell et al 2000) and video technologies (Tamburri et al 2000;Graham et al 2003) now offer much promise for mapping the distributions of these organisms (for a review see Båmstedt et al 2003). We urge further research on jellyfish species composition, distribution, and abundance in both coastal and pelagic habitats used by leatherbacks to explain both the role of jellyfish in the ecosystem and their relationship to leatherback turtles.…”

The Coevolution of Midwater Research and ROV Technology at MBARI

“…This capability gave rise to several significant advances in our understanding of the biological processes of midwater animals. Examples include: (1) measuring the effects of temperature on development in the siphonophore Nanomia bijuga (Sherlock and Robison, 2000); (2) determining that the medusa Mitrocoma cellularia responds to water-borne chemical cues for feeding (Tamburri et al, 2000); (3) learning that Aequorea victoria requires a dietary source of luciferin for bioluminescence, despite its long-standing reputation for being an intrinsic source for this photoprotein (Haddock et al, 2001); (4) discovering new bioluminescent systems in Vampyroteuthis infernalis (Robison et al, 2003); (5) demonstrating the direct uptake of dissolved organic matter by gelatinous animals (Skikne et al, 2009); and (6) establishing that deep-sea squid species grow more slowly and live longer than their shallow-water counterparts (Hoving and Robison, 2017).…”

“…MBARI's ROVs also enable manipulative, experimental work to be conducted on live specimens in situ, following the institutional priority to "take the laboratory into the ocean. " In some cases, this approach is used to confirm or refute hypotheses that have been tested first in the laboratory ashore (e.g., Tamburri et al, 2000;Bush, 2012). Another approach is to conduct the entire operation at depth with the ROV.…”

Mesopelagic zone ecology and biogeochemistry – a synthesis

“…Chemoreception enables the hydromedusa Mitrocoma cellularia to sense prey (Tamburri et al, 2000), and the behavior of many gelatinous predators suggests that this capability is widespread. A number of fishes have large nasal rosettes and expanded olfactory lobes in their brains (Marshall, 1971), presumably for finding food they cannot see.…”