SOLENODONS ARE VENOMOUS MAMMALS

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SOLENODONS ARE VENOMOUS MAMMALS

Q. I heard that an extinct mammal in the Dominican Republic injected venom to subdue its prey like some snakes, spiders and scorpions do. Is that true?

A. Yes, except it’s not extinct. Two species of solenodons still exist. Thought to be extinct until scientists discovered them in Cuba and on the island of Hispaniola (shared by Haiti and the Dominican Republic), these animals are among the few mammals in the world with glands that produce venom. A solenodon can inject venom either in defense or to subdue prey.

Solenodons belong to the same general grouping of animals as shrews, hedgehogs and moles. They diverged along a separate evolutionary line more than 70 million years ago while scooting between the feet of dinosaurs. Solenodons are larger than any other member of the shrew group, reaching body lengths of nearly a foot and with a tail almost as long. Solenodons have long, flexible snouts like shrews. They prey on a variety of small animals, including insects, spiders and worms; they may also eat lizards, snakes and frogs. Solenodon venom is mixed in with its saliva and delivered through a pair of lower jaw teeth with deep grooves that function like syringe needles. The toxic saliva paralyzes small animals when the solenodon bites them.

Other mammals known to have venomous saliva used to overcome prey include shrews of the eastern United States. The unrelated duckbill platypus of Australia is also a venomous mammal but in an entirely different manner. Male platypuses deliver a toxin by a sharp spur on each hind foot connected by a duct to a venom gland. Platypus venom is used in competition between males during mating and possibly in defense against predators.

Because of the solendodon’s rarity and because it lives in difficult-to-study areas, information on its biology is limited. Ramón Joel Espinal with the Ministry of Environment and Natural Resources of the Dominican Republic is one of the few scientists I know of currently conducting field research on these intriguing creatures. Solenodons have small eyes and poor eyesight. They stay hidden during the day in hollow logs, burrows, caves and rock crevices. They have a remarkable sense of smell that allows them to ferret out prey in the dark.

Even studies on solenodons in research laboratories have been limited. Nonetheless, one outstanding study published in the Proceedings of the National Academy of Sciences was conducted on solenodon venom by Nicholas R. Casewell (Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine) and colleagues. The primary focus of their research was to determine the evolutionary relationship between the venom of solenodons and that of their closest shrew relatives. Their study made great strides in unraveling mysteries of the evolution of venoms and how they are administered. But the authors make another important point about the value of such studies when they state, “Venoms are also of great medical importance, both due to the harm they can cause to people . . . and for the value of their highly selective toxins for understanding physiological processes and the development of new pharmaceuticals.” Thousands  of life forms—including snakes, spiders, caterpillars, stingrays, centipedes and jellyfish—produce venoms that affect humans. Some might view as merely esoteric research studies into a peculiar little creature they’ve never heard of on Caribbean islands. However, such studies can establish a foundation of basic knowledge of value to humans far beyond what an untrained observer might perceive.

The ancestors of solenodons trace back to a time before the dinosaurs. Those still with us offer a solemn message about environmental impacts humans can have on native species, especially on islands, even large ones like Cuba and Hispaniola. The severe decline of solenodons, which led to their being presumed extinct, is attributed to the introduction of feral cats, dogs and mongooses as well as to the destruction of natural habitats, a phenomenon that continues not only where solenodons live but also in our own country.

 Send environmental questions to ecoviews@gmail.com.

Solenodons in the Dominican Republic are larger than any of their shrew or mole relatives. Photo courtesy Ramón Joel Espinal