It’s time to dip into the “Miscellaneous” file, where I put articles that don’t fit well in the other categories. And I found a couple of articles about how animals survive in unusual environments. Our first bit of research is about sea snakes.
When I lived in Thailand, I snorkeled a lot, and, one day, I was followed by a swimming snake. I left the water immediately because they’re poisonous. They’re also reptiles, and the yellow-bellied sea snake (Hydrophis platurus) is the only reptile in the order Squamata that lives on the open sea. It has one of the largest geographic ranges of any vertebrate species.
How do sea snakes get freshwater to drink?
Unlike fish, reptiles don’t drink seawater. So how do these snakes survive in the salt water of the open ocean? In a study published in PLOS ONE, researchers from the University of Florida show that the snakes obtain freshwater from “lenses” that form on the ocean’s surface during heavy rain where the salinity at the surface decreases enough for the water to be drinkable.
The researchers captured 99 sea snakes off the coast of Costa Rica and offered them freshwater in a laboratory environment. When the rainy season began, they found that only 13% of snakes captured after the rain started accepted the offer, compared to 80% of those captured before. The rainfall apparently had quenched their thirst.
So, sea snakes drink rainwater, but how do birds that fly over the open ocean sleep? In a study published in the Journal of Avian Biology, researchers at Lund University say that at least some birds both eat and sleep while they’re airborne.
These birds fly nonstop for months
Three years ago, the Lund University team discovered that there were common swifts (Apus apus) that live in the air for up to ten consecutive months without landing. In the current study, the researchers looked at four pallid swifts (Apus pallidus) and found they’re in the air without landing for between two and three-and-a-half months, depending on the individual.
The researchers measured the movement when the wings flap using miniature data loggers attached to the birds. These loggers record activity every five minutes, and the bird's location once a month. Using this method, the researchers found that the pallid swifts are constantly airborne mainly during the winter months, the period of the year they spend in West Africa after the breeding season in Italy. The breeding season is the reason pallid swifts don’t fly for as long as the common swift. Pallid swifts lay two clutches in one season, the common swift only one.
Swifts apparently land mainly to breed and raise young, otherwise they live in the air. They eat insects while they fly, and when they have reached a high altitude and start gliding, they actually sleep for short periods.
Swifts have a high survival rate compared to many other birds. The researchers believe this is because swifts spend such a large part of their lives in the air, far away from ground-based predators. They also don’t have as many parasites.
Two animals that have adapted to live in very unusual places. It’s a pretty amazing world!