such as crabs and shrimp; bivalves and cephalopods are also consumed. Its bands of flattened teeth allow it to crush hard-shelled prey. Curiously, two Rhina ancylostoma examined in a 2011 stable isotope study were found to have fed on pelagic rather than demersal animals, in contrast to previous observations. The tiger shark (Galeocerdo cuvier) is known to prey on Rhina ancylostoma. The ray is protected by the thorns on its head and back, and it may ram perceived threats. Parasites documented from this species include the tapeworms Carpobothrium rhinei, Dollfusiella michiae, Nybelinia southwelli, Stoibocephalum arafurense, and Tylocephalum carnpanulatum, the leech Pontobdella macrothela, the trematode Melogonimus rhodanometra, the monogeneans Branchotenthes robinoverstreeti and Monocotyle ancylostomae, and the copepods Nesippus vespa, Pandarus cranchii, and P. smithii. There is a record of a Rhina ancylostoma being cleaned by bluestreak cleaner wrasses (Labroides dimidiatus). Reproduction in Rhina ancylostoma is viviparous, with the developing embryos sustained to term by yolk. Adult females have a single functional ovary and uterus. The litter size varies between two and eleven pups, and newborns measure long. Sexual maturity is attained at lengths of for males and over in females. Females grow larger than males. Human interactions Throughout its range, Rhina ancylostoma is caught incidentally or intentionally by artisanal and commercial fisheries using trawls, gillnets, and line gear. The fins are extremely valuable due to their use in shark fin soup, and are often the only parts of the fish kept and brought to market. However, the meat may also be sold fresh or dried and salted, and it is highly sought after in India. When caught as bycatch in trawls, Rhina ancylostoma is considered a nuisance because its strength and rough skin make it difficult to handle, and as the heavy ray thrashes in the net it can damage the rest of the catch. In Thailand, the enlarged thorns of this species are used to make bracelets. The International Union for Conservation of Nature (IUCN) has assessed Rhina ancylostoma as Critically endangered in 2019, delisted from the vulnerable category, along with many other guitarfish species. It is threatened by fishing and by habitat destruction and degradation, particularly from blast fishing, coral bleaching, and siltation. Its numbers are known to have declined substantially in Indonesian waters, where it is one of the large rays targeted by a mostly unregulated gillnet fishery. The IUCN has given this species a regional assessment of