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It is leap day! Every four years the niceties of the calendar give us this extra day. In the past, leap day has caused me to reflect about history, the calendar, and the ineluctable nature of time in general, but this year I am going a different direction. Instead of concentrating on the calendar aspect of the day, we will concentrate instead on “leaping.” And from there it is a short cognitive leap to the microcontinent of Madagascar where we find the masters of leaping, the lemurs.
Ring-tailed Lemur jumping (Lemur Catta) photo by Luc V. de Zeeuw
Lemurs are strepsirrhine (wet-nosed) primates endemic to the island of Madagascar. They are ancestral primates—the monkeys, apes, and hominids evolved from them (though of course these branches diverged in the Eocene and the lemurs have been evolving in their own directions for 50 million years). In fact, let me say that last sentence differently and better: monkeys (and apes and people) descended from a very lemur-like ancestor.
There are nearly 100 species of lemurs and they have spread through all sorts of evolutionary niches in Madagascar. It is hypothesized that they reached the island micro-continent by rafting there on masses of floating wood and vegetation. On Madagascar they were free to evolve in their own direction, as other primates back in the ultracompetitive African homeland went down different pathways. When humankind finally reached Madagascar 2000 years ago (from Indonesia!) there were even more strange lemurs, including some as large as gorillas, but the violent humans quickly snuffed them out (and indeed we are rapidly eating the remaining smaller lemurs out of house and home as well (or just eating them outright).
Female Sclaters lemur with open mouth (photo by “Tambako the Jaguar”)
Lemurs live in many habitats and specialize in many lifestyles. They are diurnal or nocturnal or crepuscular. They are fructivores, or herbivores, or insectivores. Some are omnivorous. With many different lifestyles come different habitats, but lemurs, like most other primates tend to be arboreal. While some lemurs imitate lorises and sloths and move with deliberate glacial slowness, the majority of lemurs have a different and far showier way of getting around—they leap from tree to tree like acrobats.
Perhaps I should say acrobats are like lemurs. Not only were the latter here first, but they are also capable of thrilling flights that would cause the most air-worthy flying Wallenda to fall down dead (literally). Using their long powerful back legs, lemurs hurl themselves into the air and then flatten out. They can thus leap up to 10 m (33 feet). And this is not an isolated leap. They can leap again and again and again…thus springing through whole jungles in a series of breathtaking bounds. The real masters of leaping—the ring-tailed lemur and Verreaux’s sifaka, hardly seem suited for any other sort of locomotion. When Verreaux’s sifaka is stranded in a tree island and is forced to cross open ground the poor creature looks quite ludicrous (see the gif below). It holds its arms above its head and leaps plaintively and swiftly across the hated land. But Verreaux’s sifaka looks utterly at home in its preferred habitat—hurling itself between spiny trees covered with razor sharp needles.
The more I read about lemurs, the more I realize I will have to come back and write more about them. It may be four years before the next leap day, but we will be back to lemurs before then!
Common Spotted Cuscus (Spilocuscus maculatus) photo by Waterdragon62
This is the common spotted cuscus (Spilocuscus maculatus) an arboreal marsupial from the Cape York region of Australia and New Guinea. The furtive nocturnal animal is seldom seen by humans, but it is quite successful and has spread through Papua New Guinea, Irian Jaya, and the Cape York Peninsula. The common spotted cuscus is a species of possums, a group of approximately 70 species of arboreal marsupials which are native to Australia, New Guinea, and Sulawesi. The Indo-Australian possums are analogous in lifestyle to the opossums of the Americas. Because of their furtive lifestyles most possums and opossums are unknown except to specialist zoologists (with the exception of the incredibly successful Virginia opossum).
Spotted Cuscus (Spilocuscus maculatus)
The common spotted cuscus is about the size of a housecat and weighs from 1.5 to 6 kilograms (3.3 to 13.2 pounds). The name is something of a sexist misnomer—among adults, only the males have blotchy spots on their grey/brown pelts. The spotted cuscus has numerous specialized features for its tree-dwelling lifestyle including nimble clawed digits on both its hands and feet, a prehensile tail, and strongly binocular vision. Its paws are particularly adapted for grabbing trees: the “palms” of its hands and feet are bare with special striations to give the animal a nimble clinging grip. Both its hands and feet have opposable grips—in fact the first and second digits of a cuscus’ forefoot are opposable to the other three digits so it can hold on to limbs with a deathlock. The cuscus has few natural enemies other than pythons and predatory birds, but if it is threatened it will bark aggressively and attack with its forepaws.
Spotted Cuscus (Spilocuscus maculatus) by Mark Moffet
The spotted cuscus mostly lives on a wide variety of plant products—leaves, fruits, seeds, and nectar, however, given the opportunity, the cuscus also eats small animals and eggs. A mother cuscus usually has only one infant, which she raises in her pouch till it is big enough to ride on her back (although occasional larger litters of up to three are known).
Infant common spotted cuscus (photo by Ryan Photographic)
The common spotted cuscus lives in dense tropical forests and mangroves. It has a lifespan of up to eleven years. So far the common spotted cuscus has not been threatened by habitat loss and indeed remains common (although increased logging in New Guinea may put pressure on some populations).
22 Oct 2007, Tufi, Papua New Guinea — A hand-raised spotted cuscus (Spilocuscus maculatus), a member of the opossum family, in Tufi, Oro Province, Papua New Guinea. — Image by © Michele Westmorland/Science Faction/Corbis
Monito del monte (Dromiciops gliroides)
Monito del monte (Dromiciops gliroides) is a tiny arboreal marsupial native to the temperate rainforests of Chile and Argentina. The name “Monito del monte” means “little monkey of the mountain” and although the tiny marsupials are not even remotely related to primates, they are clever and deft. During the cold winter months the animals hibernate in little ball-like nests which they build out of waterproof leaves and line with moss. Like the more familiar marsupials of Australia, the females have pouches where they nurse their litters of up to four offspring.
Monito del monte (Dromiciops gliroides) with tree snail
The adult animals prey on small invertebrates which live in the trees but they also supplement their diets with fruits and seeds. A particular species of Loranthacous mistletoe (Tristerix corymbosus) has evolved in conjunction with the monito del monte and relies entirely on the animal to spread its seeds. This is noteworthy because “scientists speculate that the coevolution of these two species could have begun 60–70 million years ago.” The monito del monte is not some rodentlike offshoot of the marsupial line, it is a close analog (and direct descendent) of the basal line from which all marsupials spring.
Monito del monte (Dromiciops gliroides) with human for scale
In fact, like something out of a gothic novel, the monito del monte is the only species of the sole genus of the last family of the exceedingly ancient order Microbiotheria. During the dawn of the dinosaurs, South America, Antarctica, and Australia were amalgamated together as a supercontinent Gondwana. The offspring of the original marsupials spread from South America, across Antarctica, to Australia, but then the continents drifted away from each other and evolution took a different direction in each ecoysytem. The monito del monte remained in the same sort of forest as its ancestors and changed least over the years.
Speaking of which, the Valdivian temperate rain forests where the monito del monte lives today are themselves a remnant of the great forests of Gonwana. The trees and plants which live there now are most closely related to the living plants of Australia, New Zealand, & New Caledonia, but they are closer still to the fossilized forests which lie beneath the glaciers of Antarctica. The Valdivian forest is the closest thing surviving to the great forests which once covered the iced over southern continent.
Valdivian Temperate Rainforest
The ancestors of the monita del monte—and of all other marsupials—originated in South America and spread through the Antarctic forests to Australia before the continents drifted apart during the Cretaceous. When the continent broke from Australia and drifted south into the prison of the circumpolar current during the Eocene, the forests died and Antarctica became an otherworldly landscape of ice. Yet if you wish to know what the sweeping temperate forests of Antarctica were like you can visit Chile and watch the most ancient marsupial among the tree ferns and araucaria trees of the Valdivian forest.
The Green vine snake (Ahaetulla nasuta)
The green vine snake (Ahaetulla nasuta) looks so ridiculously wicked and serpentine that it almost doesn’t look like an actual l snake but instead resembles an animated snake from a lurid 80’s cartoon. Ahaetulla nasuta is mildly toxic and feeds on lizards and tree frogs which it catches by means of stealth and camouflage. Native to most of southern India, the snakes are diurnal and arboreal. Their great specialization is imitating tangled green vines, a feat which they pull off so successfully that most people never notice them, however, when startled they are capable of changing their color from bright green (which blends with the jungle) to a checkered black and white warning pattern. In duress they also gape open wicked smiles to threaten off potential predators. The snakes are viviparous and have astonished zookeepers by giving birth after being alone for years. It remains a matter of herpetological dispute as to whether the female snake is able to delay fertilization within her body for extremely long periods of time or whether she is capable of parthenogenesis (a rare but not unheard of trait among snakes).
The Green vine snake (Ahaetulla nasuta) displaying a threat posture. Photo bySandilya Theuerkauf
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