Evolution and systematics
The Australian honey possum, Tarsipes rostratus, was previously labeled together with different Australian possums within the household Phalangeridae. It was deemed uncommon sufficient to deserve its personal subfamily (Tarsipedinae), but it surely was not till the mid-1970s that the true extent of its uniqueness turned obvious. Today, this tiny possum is thought to be one of the divergent marsupials, simply worthy of its family, Tarsipedidae. It is the only real survivor of an in any other case extinct marsupial group that diverged from the diprotodont lineage in the course of the Pleistocene, about two million years in the past. In this comparatively brief geological time span, the lineage has developed quickly and developed one of the specialised life of any mammal group. Its closest kin seem to be the feather-tailed possums and gliders of the household Acrobatidae. The taxonomy for this species is Tarsipes rostratus Gervais and Verreaux, 1842, Western Australia, Australia.
The honey possum is a dainty animal, tailored for climbing. Its arms and ft bear lengthy, greedy, monkeylike fingers and toes. As in all diprotodont marsupials, the second and third toes of the hind ft are fused, or syndactylous. Only the fused toes of the hind foot have claws, that are used for grooming. The different digits are geared up as an alternative with a small, spherical nail. The first toes are opposable, like these of a climbing primate. The honey possum’s agility is tremendously enhanced by its lengthy tail, the tip of which is prehensile. The tail is used as a counter-balance, a security line, and a fifth limb. It could be very sparsely haired, and bare on the underside towards the tip. The naked pores and skin supplies wonderful grip when the tail is curled round branches and stems. The honey possum’s head is distinctive, with a protracted, shrewlike snout bearing lengthy whiskers. The tongue is longer nonetheless and might be prolonged the size of the pinnacle past the tip of the snout. The enamel are decreased. Only the decrease entrance incisors are in any respect developed, whereas the others are little greater than weak pegs. The fur is coarse and grayish brown, with very lengthy guard hairs. The honey possum’s eyes are massive, as befits a nocturnal animal, and located in order that they face each ahead and upward. This association combines the benefits of binocular imaginative and prescient, which they want to transfer confidently round a three-dimensional atmosphere, in addition to be alert for airborne predators reminiscent of owls.
Honey possums have a really restricted distribution. They stay within the excessive southwestern nook of Australia, hemmed in to the south and west by oceans, to the east by the huge desert of the Nullabor and to the north by excessive floor.
Within its restricted vary, the honey possum lives solely on the sandy and coastal heaths, the place circumstances swimsuit nectarrich myeartles, proteas, banksias, and different flowering crops that, between them, bloom all year long.
Honey possums are nocturnal. Their foraging conduct is a cross between that of a monkey and a honeybee—they scurry nimbly in regards to the branches of flowering bushes and shrubs, pausing usually to thrust their snout into each floret. Being small, the honey possum makes use of a whole lot of vitality holding heat and, when resting in cool circumstances, it curls up to cut back its floor space. For a lot of the 12 months, the animals stay alone and relaxation in tree holes or deserted chicken nests. In durations of food shortage, the honey possum runs low on vitality and is typically compelled into durations of inactivity throughout which it enters a deep lethargic sleep; its coronary heart price is decreased and its physique temperature drops. Under these circumstances, a number of animals might cluster collectively as a result of, by sharing small quantities of physique warmth, they will save extra vitality nonetheless. They wake periodically and when issues have improved, they resume diligent solitary feeding to replenish their depleted reserves.
Feeding ecology and weight loss plan
The enamel of honey possums are few and underdeveloped— little greater than brief pegs incapable of biting or chewing. Despite their widespread identify, honey possums hardly ever eat honey. In truth, they feed roughly completely on pollen and nectar, a weight loss plan that makes them extremely uncommon amongst mammals apart from bats. In a dramatic instance of convergent evolution, these tiny marsupials are geared up with a protracted tongue, like that of nectar-feeding bugs or hummingbirds, with which they will attain into the nectaries of deep flowers. Unlike an insect proboscis, nonetheless, the tongue will not be tubular. Instead, it bears at its tip a extremely specialised association of bristles, like a tiny brush. This collects pollen grains and sticky nectar and delivers them into the possum’s mouth the place they're sucked off or scraped onto ridges on the roof of the mouth. Even in very small doses, this weight loss plan supplies ample sugar and protein to gasoline and keep a small physique, as long as there's a roughly steady provide.
Female honey possums are bigger than males and socially dominant. They can come into breeding situation at any time of the 12 months, offering food is plentiful, although there may be usually a lull throughout mid-summer when nectar and pollen are much less plentiful. Males collect round an estrous feminine and compete for the precise to mate, earlier than transferring rapidly on. Amazingly for such small animals, the sperm produced by males are very massive—at 0.01 in (0.three mm), they're the longest of any mammal. As if to redress the stability, feminine honey possums give delivery to the smallest mammalian infants, every one weighing not more than 0.002 oz (5 mg). Most females will mate once more nearly instantly after giving delivery. This second litter is an insurance coverage coverage—the fertilized eggs don't develop past a really early stage till the earlier litter has left the pouch or died. Hence, whereas honey possum gestation requires solely three weeks, pregnancies can final anyplace up to 13 weeks. Litters by no means comprise greater than 4 younger; that is the utmost quantity a feminine can suckle on the 4 teats in her pouch. The litter spends about eight weeks within the pouch, throughout which era every child grows to about 0.1 oz (2.5 g), which is a exceptional 500 occasions its delivery weight. After that, the younger are too huge to match within the pouch and the feminine deposits them in a spherical woven nest till they're weaned at about 10 weeks of age. A wholesome feminine will usually rear two litters in a 12 months, however will hardly ever stay lengthy sufficient to breed a 3rd time.
This species stays widespread in areas of appropriate habitat, regardless of predation by launched carnivores reminiscent of foxes and cats. The largest menace comes from habitat loss due to urbanization and land improvement, however conservation authorities are monitoring the scenario carefully to be sure that this distinctive marsupial lineage continues.
Significance to people
Honey possums are fashionable animals, although their secretive, nocturnal life make them troublesome to see. They do no hurt to human pursuits and carry out a useful service in serving to to pollinate many species of heathland flower.