Mammals
Solenodon
Solenodon paradoxus · also called solenodon, hispaniolan solenodon
The solenodon is a living fossil in the most literal sense — its lineage split from all other mammals around the time the dinosaurs still ruled, and only two species survive, on Hispaniola and Cuba. It is also one of the very few venomous mammals, injecting toxic saliva through a groove in its lower teeth.
Overview
Solenodons live in forested and scrubby areas of Hispaniola, with a separate species on Cuba, sheltering in burrows by day. About 28–33 cm plus a long tail, shaggy and small-eyed, with a long flexible snout, they dig insects, worms, and small vertebrates from the soil.
A venomous mammal
It delivers toxic saliva through a deep groove in its second lower incisor, one of only a handful of living mammals known to be venomous.
A snout on a ball joint
Its long snout attaches to the skull by a ball-and-socket joint, letting it probe into crevices and burrows with unusual freedom of movement.
Status
The solenodon is Endangered and decreasing, with little defence against introduced dogs, cats, and mongooses and ongoing forest loss.
Solenodon: common questions
Is the solenodon really venomous, and how does its venom work?
Yes, the solenodon is one of the very small number of living mammals confirmed to be venomous, alongside a few shrews, the platypus, and some other rare cases. It produces toxic saliva in a modified salivary gland located in the lower jaw, and this saliva flows along a distinct groove running down the second incisor tooth on each side of the lower jaw, so that when the solenodon bites, the venom is channelled into the wound. The venom is used primarily to help subdue invertebrate and small vertebrate prey rather than for defence, and while a bite can be painful to a human, it is not considered life-threatening to people.
How old is the solenodon lineage?
Molecular studies estimate that the solenodons diverged from the ancestors of all other living mammals roughly 70 to 80 million years ago, placing that split in the late Cretaceous period, before the mass extinction that wiped out the non-bird dinosaurs. This makes the two surviving solenodon species living representatives of an evolutionary branch that is far older than most familiar mammal groups and that has otherwise left no other survivors, so studying them offers scientists a rare window into an extremely early stage of mammal evolution that is normally accessible only through fossils.
Why is the solenodon endangered?
The core problem is that solenodons evolved over millions of years on Caribbean islands that had no native ground predators capable of threatening an adult, so the species never developed effective defences or wariness against them. When humans introduced dogs, cats, and later the small Indian mongoose to Hispaniola and Cuba, these predators found the slow-moving, ground-dwelling solenodon an easy target, and predation from them, combined with extensive clearance of the forest and scrub habitat the solenodon depends on for foraging and burrowing, has fragmented and reduced populations to the point where the species is considered at serious risk.
What is the solenodon's snout joint for?
Unlike the fixed snouts of most mammals, the solenodon's long, flexible snout is attached to its skull by a ball-and-socket joint, similar in principle to a shoulder or hip joint, which gives the snout an unusually wide range of independent movement in almost any direction. This lets the solenodon push its sensitive nose deep into narrow rock crevices, rotting logs, soil burrows, and dense leaf litter and move it around inside these spaces to locate and flush out the insects, worms, and other small prey it feeds on, effectively using the snout as a probing tool that a rigid nose could not match.