The Surinam toad, it is the most un-frog-like frog you are ever likely to see if you can see it at all, says Nick Baker, and is definitely worthy of a place on our weirdest frogs list.
Where does the Surinam toad live?
This fully aquatic frog lives in slow moving water of rainforest pools across the Amazon Basin
What does the Surinam toad look like?
The Surinam toad’s body is a soft, flattened rectangle of flesh with a leg on each corner – those at the back are chunky and webbed for propulsion; those at the front are spindly with splayed fingers reaching out. The head is a shallow triangle, all mouth, coming to a small, pointed snout.
The strange tiny eyes embedded on top of the head offer nothing familiar to fix upon. Besides, they are barely used in these dark and dingy flooded forests, where the frog’s flattened form allows it to slip unseen between submerged leaf litter.
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How does the Surinam toad catch its prey?
As it is entirely aquatic, the Surinam toad is free from the constraints of needing to move on land – it’s a non-amphibious amphibian in that respect. Instead, it has specialised as an ambush predator in the leafy pools and backwaters.
Scattered over the frog's body are strange linear patterns, as if it has been crudely sewn together. These are ‘lateral lines’, similar to those found in fish, that sense pressure changes and vibrations in the water, allowing the animal to detect prey (and predators) without needing to see it.
Another special piece of sensory apparatus used to identify prey can be found at the ends of the frog's permanently spread front toes. Each is divided at the tip into ‘quadrifurcated lobes’, meaning that each of the four lobes is further divided into four – a detail that gives the species its alternative name of star-fingered toad.
Such super-sensitivities come into play when a worm, crustacean or small fish comes blundering along. As soon as prey is in range, the frog snaps open its jaws and expands its mouth cavity – an effect further enhanced by the fact that its internal organs are shunted backwards, increasing its body volume by one and a half times – all in less than 24 milliseconds!
This explosive expansion creates massive negative pressure, sucking in water and prey. The frog’s front feet are then flung up to its face as it greedily shovels in any stray fins and limbs, before being used as strainers, allowing the expulsion of excess water while preventing its prey from swimming out.
How does the Surinam toad reproduce?
Things get even weirder during reproduction. The smaller male sings to attract a female, but rather than a frog chorus, it’s that odd mechanical ticking. When he eventually finds a partner, he dances with her, swimming loop-the-loops while hugging her body in an embrace known as amplexus.
How does the Surinam toad give birth?
While she is laying up to 100 eggs, the male fertilises them. The sticky spawn is then caught on the female’s back and the male spreads it out with gentle stokes of his rear legs. Within 24 hours the eggs sink into the spongy flesh, eventually becoming embedded and sealed over. Safe under her skin, they hatch and complete their development to tadpoles.
Once they near emergence, the female's thin skin bulges and pulsates with the struggles of the impatient froglets within. The day comes when she gives a shrug and the cells rupture, releasing tiny but perfectly formed Surinam toads into the world.
Illustrations by Peter David Scott/The Art Agency