What's more disturbing: a scuttling spider, or one that cartwheels almost as fast as a human walks? Let's take a look at...
- Cartwheeling snakes
- Leaping leeches
- Tumbling spiders
- Jet-propelled flying squid
- The skink that swims through sand
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| Sandfish skinks "swim" through the sand, avoiding the dangerous surface... (Wolfgang_Hasselmann) |
Cartwheeling Snakes
Snakes are known for their slithering, sliding and even gliding... but the dwarf reed snake cartwheels out of danger!
The reptile coils itself into an s-shape and pushes off the ground with its tail. As it tumbles forwards the head touches the ground and the body moves above then past it, effectively cartwheeling the snake. This can be repeated to keep the snake in motion.
Though it seems like an odd choice of movement, it is pretty quick - the 25cm snake can cover 1.5 meters in 5 seconds, which isn't bad for its size. The movement can also startle a potential threat, while minimizing contact with the ground and making it harder to track by scent.
The trade-off is the energy cost of cartwheeling - something the reptile mitigates by using slopes, given the chance!
Leaping Leeches
Most leeches are pretty laid-back, waiting for a blood-filled creature to brush against them... but footage of leeches in Madagascar suggests that this isn't always the case.
Though related to worms and equally boneless, leeches are more muscular than their cousins. This allows them to be a bit more gymnastic, holding on to the edge of leaves and waiting for prey to walk underneath them. The Chtonobdella leeches observed in Madagascar use this muscle to rear back like a snake, before lunging forwards and launching themselves in a short but effective hop.
There have been plenty of anecdotal reports (but no confirmed evidence) of leeches jumping on prey throughout history. This lends credibility to the idea!
Tumbling Spiders
Spiders on the shifting sands of Namib have to keep their eyes on the sky. The area is host to predatory wasps that want nothing more than to paralyze the arachnids and use them as a living nursery. The spiders dig burrows that make it hard for the wasps to enter - fighting them off head-to-head or even collapsing the tunnel on them. The wasps respond by digging pits into the burrows, sometimes excavating 300 times their own mass in sand to break in. In the face of such determined invaders, fleeing is the only option for the arachnid.
The golden wheel spider is at a disadvantage against an airborne wasp, so it has to do something that evens the odds. Presented with a threat, the spider will run, then hurl itself into a cartwheel down a slope using the joints of its legs like a roll cage. The spiders are able to cover about 1 meter per second using this method - it also blurs their outline and leaves only a faint set of tracks, giving them a chance against the wasp.
Another species of spider from Morocco can also flip away when provoked - this gives them a surprising turn of speed, allowing them to cover two meters per second!
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| Many leeches feast on blood - and some Madagascan ones can leap! (Theresamcgee) |
Jet-Propelled Flying Squid
You've probably heard of flying fish - but did you know flying squid (such as the Japanese flying squid and the neon flying squid) exist as well?
Squid propel themselves through the water by sucking water into their body and forcing it back out like a jet. With some species reaching 40kph under water, it was perhaps inevitable that some of the creatures would shoot above the surface to escape predators.
Using their bodies like organic missiles, the squid jets downwards to thrust itself out of the water. By splaying out their tentacles and using the "fins" at the other end of their body, these cephalopods act like kites and zoom above the surface of the water at 11.2 meters per second.
Some scientists speculate that if the squid adjusted the angle of its fins and "jet" it could achieve natural jet-propelled flight.
The Skink that Swims in the Saharan Sands
The sandfish skink is native to the Sahara, and with a name like that you'd expect it to be good in the desert. Still, you might be surprised to see how quickly this lizard moves through sand.
Other animals rely on a network of tunnels, but the sandfish actually swims. After rapidly forcing itself beneath the surface with short but powerful limbs, the skink tucks arms and legs close to its body and undulates, rippling in an s-motion. This propels it through both loose and packed sand - in fact, it seems to do better the more packed the sand is.
This lizard has a number of features that make this possible. A wedge shaped snout helps breach the sand, while clear eyelids protect the eyes while allowing limited vision. Steel-hard, seemingly-frictionless scales allow the creature to wriggle through the sand with little resistance.
The sandfish can cover a body-length in under a second, which is comparable to what a human Olympic swimmer can do in water. It uses this ability to swim beneath insects, bursting from the sand and gobbling them up!
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