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These snakes make up the genus Langaha, with three species total, all endemic to the island of Madagascar. 

The “noses” of each species do look different — the nose of the Ambilobe leaf-nosed snake (pictured top right) looks like the end of a broken branch, for instance. But the most striking variance exists between the sexes. Male Malagasy leaf-nosed snakes possess straighter, pointier protrusions, while those of females are frillier and more leaf-like. 

Why the sexual dimorphism? There are a few theories.

One is that these differing protrusions create different search images (the mental templates predators use to recognise their prey), making it harder for hawks, mongooses, and fossas to memorise exactly how the snakes look, thus making it harder to find them.

Another theory revolves around niche-differentiation and partitioning. The male, with his straighter nose, mimics straight twigs or thin, hanging vines. He can catch the smaller, faster lizards that frequent the thin outer branches. The female, with her frayed nose, mimics rough bark, lichen, diverging buds, or a snapped branch. She hides among the textured branches of the interior to ambush larger prey. The two sexes “partition” out the tree, so they can live in the same territory without starving each other out. 

The final theory is an expansion of the last one: rather than just partitioning niches, the two sexes partition entire habitats, in a way. These snakes live both in Madagascar's lush rainforests and scrubby dry forests — with the male more camouflaged in the former, and the female in the latter. And whichever sex is at an advantage in any given habitat, is the one that actively seeks out a mate. This allows the species to survive and breed across varied habitats. Or so the theory goes.

It’s always difficult to find definitive answers for evolutionary questions. All of these theories may be correct or none of them may be quite right. Naturally, it’s quite hard to study species that evolved not to be seen.

Learn more about these leaf-nosed snakes, and other cryptic species, here!

These snakes make up the genus Langaha, with three species total, all endemic to the island of Madagascar. 

The “noses” of each species do look different — the nose of the Ambilobe leaf-nosed snake (pictured top right) looks like the end of a broken branch, for instance. But the most striking variance exists between the sexes. Male Malagasy leaf-nosed snakes possess straighter, pointier protrusions, while those of females are frillier and more leaf-like. 

Why the sexual dimorphism? There are a few theories.

One is that these differing protrusions create different search images (the mental templates predators use to recognise their prey), making it harder for hawks, mongooses, and fossas to memorise exactly how the snakes look, thus making it harder to find them.

Another theory revolves around niche-differentiation and partitioning. The male, with his straighter nose, mimics straight twigs or thin, hanging vines. He can catch the smaller, faster lizards that frequent the thin outer branches. The female, with her frayed nose, mimics rough bark, lichen, diverging buds, or a snapped branch. She hides among the textured branches of the interior to ambush larger prey. The two sexes “partition” out the tree, so they can live in the same territory without starving each other out. 

The final theory is an expansion of the last one: rather than just partitioning niches, the two sexes partition entire habitats, in a way. These snakes live both in Madagascar's lush rainforests and scrubby dry forests — with the male more camouflaged in the former, and the female in the latter. And whichever sex is at an advantage in any given habitat, is the one that actively seeks out a mate. This allows the species to survive and breed across varied habitats. Or so the theory goes.

It’s always difficult to find definitive answers for evolutionary questions. All of these theories may be correct or none of them may be quite right. Naturally, it’s quite hard to study species that evolved not to be seen.

Learn more about these leaf-nosed snakes, and other cryptic species, here!

Researchers discovered this species off the northeastern coast of Taiwan, collecting six specimens across four years. Why did it take so long? Between October and April, the sea turns cold and harsh, while typhoons buffet the coast between May and September. They could only dive — to depths between 18 and 30 metres (59–98 ft) — when the weather permitted.

This species gets its specific name, sesama, from the yellow and black spots that cover its entire translucent body like sprinkled sesame seeds. Between those spots, it’s also speckled with pretty, snowflake-like markings.

Fittingly for a “sesame seed sea slug,” the largest individuals recorded were only about as large as a single sesame seed. To be precise, measurements ranged from 0.9 to 2.95 millimetres or 0.035 to 0.1 inches. This is much smaller than other species in its genus, such as T. picta, which can grow to be up to 20 millimetres (0.8 in) long — six or seven sesame seeds. 

Like most nudibranchs, T. sesama is a specialist predator, “specifically observed feeding on one species of bryozoan [a tiny colonial animal].” 

Thecacera sesama was the seventh species described in its genus. Two other named Thecacera live alongside it, feasting on the same bryozoans, as well as a whole five species yet to be described.

Read more about this sesame seed sea slug here!

Chan H-Y, Lee C-L, Chen W-C, Chang C-H, Shao Y-T, Pang K-L (2026) Thecacera sesama sp. nov. (Nudibranchia, Polyceridae) from Taiwan, evident from morphology and phylogenetic analyses of the 16S rDNA and cytochrome c oxidase I gene. ZooKeys 1279: 269-284. https://doi.org/10.3897/zookeys.1279.184298

Endemic to the island of South Georgia, this species has uncharacteristically long legs and hindclaws for a pipit, which it uses to navigate the thick tussac grass and rocky shores where it hunts for dwarf spiders, bog beetles, and kelp flies (among other invertebrates).

It has evolved significantly thicker feathers than its more equatorial mainland relatives to provide insulation from the "Roaring Forties" and "Furious Fifties” — incredibly strong winds that whip across the Southern Ocean — and temperatures that, on average, hover around freezing.

During the breeding season, males perform spectacular aerial song displays, hovering high above the cliffs before parachuting down. There are also reports of “the bird's lark-like rising, fluttering, and lovely singing.” (Pagenstecher, 1884).

For two centuries, invasive brown rats and house mice (introduced by sealers and whalers) preyed on the pipit's eggs and chicks, pushing the species to take refuge on tiny offshore islets. However, following the world’s largest rodent eradication project — taking seven years to complete — the island was declared completely rodent free in 2018. The South Georgia pipit has reclaimed its island and the species is now listed as Least Concern by the IUCN.

Learn more about this pipit, and the operation that saved it from likely extinction, here!