Abstract:
Three studies on the invertebrate corallivore Hermodice carunculata, commonly known
as the bearded fireworm, were conducted to provide baseline information on the general
anatomical features, nutritional requirements, feeding behavior, and growth rates of this
poorly documented reef inhabitant. Through histological techniques, the species’ feeding
mechanisms, digestive system, and sensory structures were studied to understand its
ability to adapt to a changing reef habitat. Several previously unreported features were
observed including a simple layer of cells on the outer cuticle resembling, and the size of,
bacteria, a specialized tissue in the foregut, and pigment granules penetrating the ventral
cuticle at the nerve cord connection. This study also documented the appearance of gut
content in the digestive tract and the presence of secretory cells on the proboscis. These
observations provide insight into the feeding behavior of H. carunculata. Ex situ feeding
experiments were conducted in Barbados to monitor organisms’ weight change in
different coral reef feeding regimes as an indication of nutritional value of coral species.
During the experiments, H. carunculata specimens experienced a Millepora complanata
feeding regime and a short time period in a Montastraea annularis feeding regime. In
both experiments, the average weight change was not statistically significant, which
indicates the H. carunculata specimens did not gain weight in the presence of M.
complanata. These results suggest H. carunculata may supplement their diet with other
food sources to meet nutritional requirements. Finally, during an outbreak of an
unknown white syndrome on coral colonies in the Flower Garden Banks National Marine
Sanctuary, field samples, including H. carunculata specimens associated with the coral
tissue loss margins, were collected to test the use of the Polymerase Chain Reaction
(PCR) and DNA fingerprinting to identify H. carunculata associated with tissue loss
lesions. Specific H. carunculata primers were designed to amplify H. carunculata DNA
in the samples. The H. carunculata tissue samples (positive controls) were the only
samples amplified during the PCR tests. These results suggest H. carunculata organisms
do not leave detectable amounts of DNA at foraging sites. However, future molecular
tests should be conducted using other target sequences for amplification and take into
considerations the sensitivity of conditions including the number of PCR cycles.
