Grab-and-Go Beetle Hoards Poo and Gallops
New research shows that the diarrhea-like waste from whales is rich in iron so it stimulates the growth of phytoplankton, which then serve as carbon traps that remove some 400,000 estimated tons of carbon from the atmosphere each year.
Capt. Joe Borkowski III and Nick Gales
This photograph shows an Antarctic minke whale in the Southern Ocean. The giant gas bubble emanating from the whale suggests that flatulence is just as common for ocean mammals as it is for humans and many other terrestrial animals.
Sarah Robinson, © Commonwealth of Australia
Antarctic Division marine biologist Nick Gales scoops whale poo from water. When whales consume iron-rich krill, they excrete most of the iron back into the water. That triggers the growth of phytoplankton. The phytoplankton take up carbon from the ocean as they grow. Through the entire life and death cycle of these plants, the carbon then stays trapped for centuries.
Mike Double, © Commonwealth of Australia
A scientist collects a fecal whale sample from a net. Most whale waste is not solid, but comes out as a giant liquid plume (save for the undigested squid beaks). Other marine mammals probably beneficially redistribute carbon just as whales do. These may include seals, sea lions and sea otters.
H. Ryono, Aquarium of the Pacific
Blue and Red
Blue whale poop is shown. The red coloration is a result of the whale's krill diet. "It is sometimes thought that conservationists try to 'save the whales' only because they are cute," says Trisha Lavery a marine biologist at Flinders University of South Australia. But, as she points out, the animals (and their waste) "play a crucial role in marine ecosystems."
Given the choice between flying and hoarding dried feces, most of us would take to the air, but a certain beetle in Africa prefers to spend its time on the ground collecting poop.
“This species of Pachysoma grabs bits of poo and gallops forward with it,” Marcus Byrne of the University of Witwatersrand, was quoted as saying in a press release. “That is really odd. Most insects walk with a tripod gait. They plant three legs in a triangle, while swinging the other three legs forward. It’s an incredibly stable way of walking because you’ve always got three legs on the ground.”
“For an insect to abandon the tripod gait and use its legs together in pairs like a galloping horse is really radical. The big question is: Why are they doing it?” asked Byrne, who along with his colleagues, studied the unusual insect.
Most dung beetles gather “fresh” poop and pack it into one wet ball that they roll along the ground before their big escape. Pachysoma, on the other hand, collects bits of dry dung and hoards it in a nest. The beetle goes on repeated foraging trips instead of one major journey.
Byrne and his colleagues from Lund University in Sweden think the species might have changed its mode of navigation because it needs to be able to find its way back and forth from its nest.
“For most dung beetles, it’s always a one way trip — grab the poo, run away and never go back,” he explained. “The very marked pacing of Pachysoma‘s gallop might be giving it a better signal in terms of estimating the return distance from the food to its nest. When it gallops, it slips less in the soft sand.”
Prior research has found that ants count their steps as a way to navigate back and forth from home, and bees use the optical flow of scenery across their retinas to measure how far they’ve travelled to forage from the hive. Pachysoma dung beetles seem to be using a version of both techniques.
“Bees use optic flow as a measure of how fast and how far they’ve flown,” Byrne said. “Dung beetles have two eyes on each side of their head, one on top and one on the bottom, looking at the sand and we think Pachysoma might be registering optic flow with its bottom eye over the sand.”
But Pachysoma has not only changed the way it moves across land, it has also lost its ability to fly.
“There are 800 species of dung beetle in South Africa and most of them fly,” Byrne said. To fly makes sense because poo is a very ephemeral resource. It’s only useful for a few days and it’s very patchy — you don’t know where you’re going to find the next dropping. That’s why Pachysoma is so weird. Why would anyone give up flying?”
It could be that Pachysoma sealed up its wings in order to conserve moisture in its arid environment.
In any case, its unique ways have worked. Like a businessman settling into a niche market, this flightless dung beetle has cornered the market on dried poo in its ecosystem.
Watch one at work here.
Photo: University of the Witwatersrand