Category Archives: Insects, Fish, Frogs

Insect Plays Dead To Live Longer

Indian stick insect with shadow (photo from Wikimedia Commons)

Insects have many techniques for escaping predators. They fly, sting, use camouflage, or contain poisons. The Indian stick insect (Carausius morosus) has none of these skills so it plays dead.

John Skelhorn at Newcastle University wondered if feigning death actually works. Stick insects taste good when they’re alive but taste terrible when dead. Do predators always avoid dead-looking critters? Skelhorn experimented with stick insects and one of their predators to find out.

First, here’s what a living stick insect looks like.

For predators, Skelhorn chose chickens who’d never seen a stick insect — 90 chicken chicks divided into three test groups.

Day-old domestic chicks, Gallus gallus (photo by Fir0002/Flagstaffotos via Wikimedia Commons)

Naive chicks who’d never eaten a dead stick insect were willing to approach those playing dead. However, any chick that had tasted a dead one, moved back and refused to touch the pretender. (Eeeeww! They wiped their beaks.)

Does an insect playing dead live longer? Yes, if the predators have experience.

Read more at Scientific American The Art of Playing Dead and the original study published in Current Biology.

(photos from Wikimedia Commons; click on the captions to see the originals)

Birds Uncover Illegal Fishing

Wandering albatross (photo from Wikimedia Commons)

As human population soars and fish populations plummet illegal fishing has ramped up in the world’s oceans. With 50% of the world’s fish population now gone, countries protect fish within their 200-mile Exclusive Economic Zones (EEZ) but dishonest fishing vessels sneak in to capture endangered species and overfish what’s left.

Catching the perpetrators, or even knowing they’re out there, has been quite difficult despite the ability to track them by satellite. That’s because dishonest vessels turn off their Automatic Identification System (AIS) satellite transponders so they can’t be seen. The boats travel safely without AIS; they use radar to avoid collisions and find fish.

In 2017 Henri Weimerskirch and colleagues at Centre of Biological Studies Chiz√© launched an innovative study to uncover the extent of illegal fishing. They equipped wandering albatrosses (Diomedea exulans) with radar detectors that transmit location data to satellites. The research team then matches albatross radar sightings to AIS satellite sightings. If there’s a radar ping but no AIS, the boat is operating illegally.

Wandering albatross east of Tasman Peninsula (photo from Wikimedia Commons)

The research team expanded the study in 2019 by fitting 169 albatrosses from Crozet and two other islands with radar detectors (map below). From December 2018 to June 2019 the albatrosses encountered 353 ships, 37% of which had turned off their AIS.

Global Fishing Watch map highlighting Crozet Islands Exclusive Economic Zone (screenshot from globalfishingwatch.org)

After a 6-month study with the large seabirds, the researchers estimate that more than one-third of vessels in the southern Indian Ocean are sailing undercover, confirming concerns about illegal or unreported fishing.

Seabird cops spy on sneaky fishing vessels

Armed with this new data, enforcement can now focus on the hotspots of illegal activity. Ideally it will lead to more arrests like the one pictured below in the North Pacific in 2008.

U.S. Coast Guard seizes a Chinese fishing vessel suspected of illegal large-scale high-seas drift net fishing 460 miles east of Hokkaido, Japan. Coast Guard photo taken by USCGC Munro. 11 Sep 2008 (photo by U.S. Coast Guard via Flickr)

Read more about the albatross project in Science Magazine: Seabird cops spy on sneaky fishing vessels.

See the full study at PNAS: Ocean sentinel albatrosses locate illegal vessels.

(photos from Wikimedia Commons and Flickr, map screenshot from Global Fishing Watch; click on the captions to see the originals)

Charming The Worms, Part 2

On Friday we watched gulls charming the worms. Today we’ll watch people do it.

Perhaps you’ve noticed that earthworms come out on the sidewalks when it rains. They rise to the surface in damp soil when they hear the pattering of rain above them. Gulls and wood turtles take advantage of this by tapping on damp ground to lure worms to be eaten.

People use a variety of techniques, called worm charming, to collect worms for fish bait. The video above was taken at the annual World Worm Charming Championships in Willaston, UK.

Below, a man and wife gather worms for the fish-bait trade in Florida. He makes a noise called worm grunting while she gathers the worms.

(videos from YouTube and Wikimedia Commons)

Oh No! Spotted Lanternfly in Beaver County

Adult spotted lanternfly, wings open and closed (photos by PA Dept of Agriculture via bugwood)

It was only a matter of time before the highly invasive spotted lanternfly (Lycorma delicatula) made its way to western Pennsylvania but it’s disturbing to learn that it’s so close to Pittsburgh.

On 20 January 2020 the Columbus Dispatch reported that spotted lanternfly egg masses were found at the Norfolk Southern railyard in Conway, PA. They probably arrived by train and are now less than 20 miles from Downtown Pittsburgh and even closer to Ohio.

At this time of year the adult bugs are not active so an egg mass, pictured below, is the only thing they found. The authorities scraped away the egg masses and killed the eggs.

This is bad news anyway. USDA says that spotted lanternflies are the worst invasive species we’ve seen in the United States for 150 years.

Learn how to identify them and see why they’re so awful in the video below.

Oh no!

(photos from bugwood.org; click the captions to see the originals)

Walking Backward, They Still Get Home

Ant dragging food (photo by adrianalexalexander via Flickr, Creative Commons license). (This is not a desert ant.)

Ants are amazingly strong for their size, able to lift objects 5,000 times their own body weight and carry them back to the nest. If an object is too big to lift, the ant drags it all the way home.

We’re often so mesmerized by the ant’s struggle that we forget she has an additional challenge. She has to navigate while walking backward. Ethologists at Paul Sabatier University wondered how ants do this so they baked some cookies and ran some tests.

Using a nest of Spanish desert ants (Cataglyphis velox) the scientists laid out large cookie pieces for the ants to find. Without disturbing the ants’ paths scientists noted how often they turned around to check their bearings. They also “airlifted” some ants away from the nest (no path to remember) and messed up the scenery for others so the path would look different.

To give you an idea how hard this is, imagine walking backward without the help of handheld Google/Apple maps. How often would you turn around to check where you were going? And what would you do if an enormous hand rearranged the scenery and nothing looked the same?

Some of the confused ants never made it, but those who knew their path walked 6 meters without peeking. This is equivalent to a human walking backward without peeking for the length of two football fields.

Perhaps it helps that ants can see nearly 360 degrees around their heads. Despite all the challenges they still get home.

Read more in Science Magazine.

p.s. Desert ants don’t use pheromone trails to navigate. Instead they use many other tools including sight, body memory, the Earth’s magnetic field and the scents of other things.

(photo by adrianalexalexander via Flickr, Creative Commons license. Video from Wikimedia Commons; click on the captions to see the originals)

This Seabird Relies on Algae

Dovekie at Spitzbergen, Svalbard (photo from Wikimedia Commons)

Though this arctic seabird doesn’t eat algae it will starve if marine algae is not abundant. On Throw Back Thursday we’ll learn more with the help of two vintage articles.

About the size of a starling, the dovekie or little auk (Alle alle) breeds on islands in the high arctic including Greenland, Svalbard, and Franz Josef Land. Its population of 16-82 million birds spends the winter in the North Atlantic, occasionally as far south as Cape Hatteras. Learn more with a video in this article: Birds On Ice: Dovekie.

Dovekies eat small invertebrates and fish but the majority of their diet is made up of copepods. A single dovekie eats 60,000 of them per day. Quadrillions(*) fall prey to dovekies during the breeding season. So … What the heck is a copepod?

Copepod (photo from Wikimedia Commons)

Here’s where the algae comes in.

Copepods eat microscopic marine algae called phytoplankton that contain chlorophyll and need sunlight to live and grow. In the high arctic, the summer sun makes phytoplankton bloom, as seen below in the Barents Sea. It takes quadrillions phytoplankton to feed billions of copepods to feed the dovekies.

Phytoplankton bloom in the Barents Sea (photo by NASA from Wikimedia Commons)

Phytoplankton is really tiny, so small that you need an electron microscope to see it. The Barents Sea bloom above is thought to be Emiliana huxleyi, shown below. The disks are made of calcium carbonate which is also the primary component of seashells. The calcium in phytoplankton makes its way up the food chain.

Phytoplankton Emiliana huxleyi, magnified (image from Wikimedia Commons)

Thus if phytoplankton is scarce, copepods are scarce and the dovekies starve. That’s how a seabird relies on algae.

(photos from Wikimedia Commons; click on the captions to see the originals)

(*) How many copepods? Here’s a back of the napkin calculation: Suppose there are 50 million dovekies, each one eating 60,000 copepods/day. Dovekies live in their breeding range for four to six months, so there have to be quadrillions of copepods available during that period. Dovekies aren’t the only animal that eats copepods. The numbers are staggering! (My original calculation had a power-of-10 problem. See Tom Brown’s correction.)

Bug On My Front Porch

Larger than life, a western conifer-seed bug in Pittsburgh, 30 Oct 2019 (photo by Kate St. John)

Insects that disappeared in the cold came out again during last week’s warm weather. On Wednesday I found a western conifer-seed bug on my front porch.

Formerly restricted to the western U.S., the western conifer-seed bug (Leptoglossus occidentalis, WCSB) has spread across North America, to Europe and South America. At 1/2 to 3/4 inches this “true bug” sucks the sap of developing pine cones and the pulp of pine seeds.

WCSB can see pine cones from afar in glowing infrared colors so this one was probably lured by the cones on my neighbor’s blue spruce.

After he ate, he needed to find shelter. Wednesday’s warmth was followed by record rain on Thursday and cold wind on Friday.

Western conifer-seed bugs overwinter in a bark crevice, a dead tree, or a house. My house. I didn’t know they came inside until I researched this article. By then the bug had disappeared.

Western conifer-seed bugs stink when they’re disturbed. … Great. I can hardly wait.

(photo by Kate St. John)

A Brief Change Of Scene

The view from Fort Hill at Cape Cod, 18 Oct 2019 (photo by Kate St. John)

Travel is a tonic for seeing the world in new ways. This month my husband and I spent a week with his sister at Cape Cod where we had new weather, new scenery and new looks at plants I might have seen at home.

Our timing was pretty good. We missed the October 12 nor’easter but were on hand for the October 17 “bomb cyclone.” We didn’t lose power, but it was still very windy on the 18th when I visited Fort Hill, pictured above.

Birds were hard to find that day so I noticed plants such as this European spindle-tree (Euonymous europaeus) with puffy, pink, four-sided fruits.

European spindle-tree fruits, 18 Oct 2019, Dennis, MA (photo by Kate St. John)

The puffballs are actually a casing that holds orange fruit within. This ornamental has probably been planted in Pittsburgh, though I’ve never noticed it.

Euonymous europaeus fruits burst open (photo from Wikimedia Commons)

My favorite discovery was a hole in a leaf.

Someone ate this, Cape Cod, 20 Oct 2019 (photo by Kate St. John)

Who ate it? Perhaps this caterpillar did. I found him elsewhere on the plant.

And finally, the sun touched translucent red berries and made them glow at Bell’s Neck.

The small plants have a single leaf midway up the stem (lefthand photo) and were growing among pine needles. Please leave a comment to tell me what they are.

p.s. Thank you to Kerry Givens who identified the red berries as a Canada mayflower and the caterpillar as a Turbulent Phosphila moth.

(photos by Kate St. John except where noted in the captions; click the captions to see the originals)

Isabella Prepares For Winter

So many woolly bear caterpillars have crossed my path this fall that, fearing they’d be trampled, I have carefully moved each one across the trail.

“Woolly bears” are the larva form of a common North American moth, the Isabella tiger moth (Pyrrharctia isabella). Since she is not dependent on only one host plant, Isabella is found in many habitats.

She even lives in the Arctic, surviving the winter because she has natural anti-freeze in her cells. Wikipedia describes how she does it:

The banded woolly bear larva emerges from the egg in the fall and overwinters in its caterpillar form when it literally freezes solid. First its heart stops beating, then its gut freezes, then its blood, followed by the rest of the body. It survives being frozen by producing a cryoprotectant in its tissues.  In the spring it thaws.

from Wikipedia: Pyrrharctia isabella
A woolly bear’s face (photo by Kate St. John)

After she thaws in the spring, the woolly bear resumes eating, spins a cocoon, and becomes a flame-colored moth.

Isabella tiger moth perched on a finger (photo from Wikimedia Commons)

She’s rather large, but I don’t think I’ve ever seen her as an adult. Have you?

Adult Isabella tiger moth (photo from Wikimedia Commons)

I only notice Isabella as she’s preparing for winter.

Read about woolly bears — and what their stripes mean — in this vintage article: Isabella Scoffs At Winter.

(photos of woolly bear caterpillars by Kate St. John, photos of adult moths from Wikimedia Commons; click on the captions to see the originals)

Amazing Camouflage

This is not a leaf, it’s a butterfly (photo from Wikimedia Commons)

The orange oakleaf butterfly (Kallima inachus), native to tropical Asia, is well named. The underside looks exactly like a leaf when the butterfly closes its wings, and it has wet and dry season forms that mimic the leaves of each season.

The butterfly stands out when its wings are open.

Orange oakleaf butterfly (photo from Wikimedia Commons)

Watch it become a leaf as it flutters in place.

We have leaf-like butterflies in North America, too. Click to see the ventral and dorsal sides of the goatweed leafwing (Anaea andria). It ranges from southeastern Arizona to southern Ohio.

(photos from Wikimedia Commons; click on the captions to see the originals. video from Red Cache World on YouTube)