Crested penguin eggs, new research


This video says about itself:

20 April 2011

These are Erect-Crested Penguins on Antipodes Island, New Zealand. This video was taken by David Salomon from an inflatable Zodiac boat.

From Science News:

Why crested penguins lay mismatched eggs

Extreme penguin egg favoritism could be quirk of migration

By Susan Milius

11:00am, December 8, 2016

In crested penguin families, moms heavily favor offspring No. 2 from the start, and a new analysis proposes why. The six or seven species of crested (Eudyptes) penguins practice the most extreme egg favoritism known among birds, says Glenn Crossin of Dalhousie University in Halifax, Canada.

Females that lay two eggs produce a runty first egg weighing 18 to 57 percent less than the second, with some of the greatest mismatches among erect-crested and macaroni penguins. Some Eudyptes species don’t even incubate the first egg; royal penguins occasionally push it out of the nest entirely.

Biologists have proposed benefits for the unusual behavior: A sacrificial first egg might mark a claim to a nesting spot or improve chances of one chick surviving predators. But those ideas haven’t held up, Crossin says. He and Tony Williams of Simon Fraser University in Burnaby, Canada, propose in the Oct. 12 Proceedings of the Royal Society B that egg favoritism is just a downside of an open-water, migratory lifestyle.

Among the 16 penguin species that lay two eggs, only the Eudyptes species evolved what’s called a pelagic life, spending their nonbreeding season mostly at sea and migrating, in some cases considerable distances, to breeding sites.

Female crested penguins tend to lay their first eggs soon after arriving at a breeding site, meaning that the egg must have started its roughly 16-day development while mom was migrating. The biology of long swims, now encoded genetically, interferes with producing a full-sized egg. A puny first egg might just be a sign that mom is trying to do two things at once, Crossin says.

Male spiders caring for youngsters


This video says about itself:

5 December 2016

Rafael Rios Moura says spider moms handle most of the parental care, but not the Manogea porracea species he studied. Both spider parents take responsibility to protect their egg sac. Linda Rayor of Cornell University said, “To the best of my knowledge, there really aren’t other examples where male spiders step up to care for young or eggs.” Sometimes at the cost of their own lives, male Manogea porracea switch from solitary life to a dad-web upstairs, brushing rainwater off egg sacs. Moura hypothesizes that the females are very delicious to predators considering that many females disappeared by the end of breeding season.

From Science News:

First spider superdads discovered
Males give up solitary life to protect egg sacs, spiderlings — often as single parent

By Susan Milius

9:00am, December 5, 2016

The first normally solitary spider to win Dad of the Year sets up housekeeping in a web above his offspring and often ends up as their sole defender and single parent.

Moms handle most parental care known in spiders, says Rafael Rios Moura at the Federal University of Uberlândia in Brazil. But either or both parents care for egg sacs and spiderlings in the small Manogea porracea species he and colleagues studied in a eucalyptus plantation. The dad builds a dome-shaped web above the mom’s web, and either parent will fight hungry invaders looking for baby-spider lunch. In webs with no parents, only about four spiderlings survived per egg sac. But with dad, mom or both on duty, survival more than doubled, the researchers report in the January 2017 Animal Behaviour.

“To the best of my knowledge, there really aren’t other examples where male spiders step up to care for young or eggs,” says Linda Rayor of Cornell University, who has studied spider maternal care. In a group-living Stegodyphus species, some of the males in a communal web will attack intruders, but Manogea dads do much more. They switch from solitary life to a dad-web upstairs, brush rainwater off egg sacs and share defense, sometimes at the cost of their own lives.

Many male web-building spiders stop feeding as adults because they’re out searching for mates instead of catching food with their web, Moura says. Manogea males, however, stick with a female they mated with and build a new food-catching web. Now Moura would like to know whether such commitment makes males unusually choosy about females, he says.

To predators, females “must be very delicious,” Moura says. In the wild he found that many females disappeared, probably eaten, by the end of the breeding season, leaving dads as the sole protector for 68 percent of the egg sacs.

That high female mortality could have been important for evolution of the dads’ care-taking, says behavioral ecologist Eric Yip of Penn State. Just why this species has such high female mortality puzzles him, though.  Females, geared up for egg-laying, have rich nutrient stores. Yet, he says, “that’s generally true for all spiders — that females are going to be more nutritious and males are going to be mostly legs.”

Bird flight, new research


This video says about itself:

5 December 2016

Using a high-speed camera, scientists captured the swirling vortices produced by a slowly flying bird. Surprisingly, they found that the vortices rapidly dissipated. The unexpected effect suggests that scientists need to rethink methods for calculating the lift produced under such conditions.

From Science News:

Bird plus goggles equals new insight into flight physics

Unexpected vortices form in parrotlet’s wing wake

By Emily Conover

6:21pm, December 5, 2016

A bird in laser goggles has helped scientists discover a new phenomenon in the physics of flight.

Swirling vortices appear in the flow of air that follows a bird’s wingbeat. But for slowly flying birds, these vortices were unexpectedly short-lived, researchers from Stanford University report December 6 in Bioinspiration and Biomimetics. The results could help scientists better understand how animals fly, and could be important for designing flying robots (SN: 2/7/15, p. 18).

To study the complex air currents produced by birds’ flapping wings, the researchers trained a Pacific parrotlet, a small species of parrot, to fly through laser light — with the appropriate eye protection, of course. Study coauthor Eric Gutierrez, who recently graduated from Stanford, built tiny, 3-D‒printed laser goggles for the bird, named Obi.

Gutierrez and colleagues tracked the air currents left in Obi’s wake by spraying a fine liquid mist in the air, and illuminating it with a laser spread out into a two-dimensional sheet. High-speed cameras recorded the action at 1,000 frames per second.

The vortex produced by the bird “explosively breaks up,” says mechanical engineer David Lentink, a coauthor of the study. “The flow becomes very complex, much more turbulent.” Comparing three standard methods for calculating the lift produced by flapping wings showed that predictions didn’t match reality, thanks to the unexpected vortex breakup.

Fijian ants as agriculturists


This video says about itself:

27 November 2016

Scientists on the island of Fiji have discovered a type of ant that plants, fertilizes & guards its own coffee crops. The ant, known as “Phildris nagasau” has been perfecting this practice for millions of years. The ants reportedly don’t just harvest the nectar from the plants, they also use the coffee plants as a place to live. According to the scientists, this is the first ant to build its own home. In an experiment, researchers discovered that the ants plant six different types of coffee plant in the bark of jungle trees.

From Nature:

Obligate plant farming by a specialized ant

Guillaume Chomicki & Susanne S. Renner

21 November 2016

Abstract

Many epiphytic plants have associated with ants to gain nutrients. Here, we report a novel type of ant–plant symbiosis in Fiji where one ant species actively and exclusively plants the seeds and fertilizes the seedlings of six species of Squamellaria (Rubiaceae). Comparison with related facultative ant plants suggests that such farming plays a key role in mutualism stability by mitigating the critical re-establishment step.

Why vultures can eat dead animals


This video from the USA says about itself:

Why Vultures Don’t Get Sick When Eating Dead and Rotting Things

In the video today we’re looking at why vultures can happily eat various dead and rotting things, even when said flesh is disease ridden, all without apparent negative effect on themselves.

Carnivorous plants helped by bacteria


This video from Malaysian Borneo says about itself:

9 February 2007

David Attenborough looks at another meat eating plant – the pitcher plant and how it catches insects. From the BBC.

From Science News:

Bacteria help carnivorous plants drown their prey

Microbes alter surface tension in the water traps of pitcher plants

By Susan Milius

7:05pm, November 22, 2016

Bacteria may be a meat-eating plant’s best friends thanks to their power to reduce the surface tension of water.

The carnivorous pitcher plant Darlingtonia californica releases water into the tall vases of its leaves, creating deathtraps where insect prey drown. Water in a pitcher leaf starts clear. But after about a week, thanks to bacteria, it turns “murky brown to a dark red and smells horrible,” says David Armitage of the University of Notre Dame in Indiana. Now, he’s found that those bacteria can help plants keep insects trapped. Microbial residents reduce the surface tension of water enough for ants and other small insects to slip immediately into the pool instead of perching lightly on the surface, he reports November 23 in Biology Letters.

Armitage seeded tubes of clean water with fluid from the trap pools of pitcher plants and added dead crickets to feed the microbes. After sitting for a month, the mess had about the same surface tension properties as natural pitcher plant pools. Then, he created a series of increasingly dilute samples of pool soup and dropped harvester ants into each one. He found that the ants sank immediately in all but the bacteria-free water sample.

Bacterial populations in a pitcher leaf are akin to those in a mammal gut or bovine rumen, Armitage’s preliminary analysis finds. The microbes can help digest the prey as well as catch it, he says.