On Phoroncidia

A few years ago I got an email from Mark Stowe, of bolas spider fame, asking about a spider we had collected in the work we had done on the spiders that live in the epiphytes of the tree canopies in shade coffee plantations. He was very interested in Kaira sp, and asked if we had a specimen. I looked into our data base, and then to the collection, but we had found only one specimen and that one was currently in the arachnid collection of Fernando Alvarez Padilla in the UNAM. After that exchange, I looked up a bit about Kaira and it had a very weird shape, and in this way I sort of memorised the general shape of the body, a technique that birders use to identify birds in flight.

And so, when I did see one after a couple of years, it was the merest glimpse of it, a small stubby jutting out against a macadamia leaf on the tree that grew alongside my balcony that triggered my memory. I looked closely and lo, it was a Kaira! I watched it for a while, it rarely moved, I took some photos and notified Mark, but for one reason or the other it never went beyond that.

After that encounter, I got into the habit of scanning the tree every time I was out on the balcony. A couple more Kairas turned up but disappeared after a while. Then one day a slightly differently shaped spider made its presence felt to my eyes. (I can’t say I saw it, it just appeared in my vision).

I was hard pressed to identify it, by itself not so surprising since I am still getting to know the spider fauna of Mexico. It was just out of reach for a decent photograph.

I quickly ran though my mental spider database and thought it could be an orb web spider of some sort that builds a web at night. But when I checked it out at night it was hanging off a single web strand. Then it clicked. It must be Phoroncidia! A theridiid spider that uses just a single web strand to hunt prey.

I read up about it, and though most people think that insects hit the web by accident, Eberhard suggests that the web contains glue which may have insect attracting compounds. I waited for a long time hoping to catch a predation event in action, but I had no luck. I did find some flies stuck on the web though. I took a series of photos, and even caught it making an eggsac, but not once did I see an insect actually land on the web.

Sea level rise in legends

I fell into an another rabbit hole the other day, I saw a link to a paper titled "Aboriginal Memories of Inundation of the Australian Coast Dating from More than 7000 Years Ago". The paper put together a series of legends about sea level rise from indigenous Australian sources from all around the continent and connected it to geological records showing that there exists cultural memory of inundation and large scale sudden shifts in the topography of the sea shore. There are a series of accounts of how once it was possible to walk to certain islands or that there were certain islands that completely vanished. The paper also notes that floods are a very common theme in many cultural accounts, and attributes this to the thawing after the post glacial period. The startling claim is that humans retain a cultural memory of events of more than 7000 years ago.

Here’s the abstract
Stories belonging to Australian Aboriginal groups tell of a time when the former coastline of mainland Australia was inundated by rising sea level. Stories are presented from 21 locations from every part of this coastline. In most instances it is plausible to assume that these stories refer to events that occurred more than about 7000 years ago, the approximate time at which the sea level reached its present level around Australia. They therefore provide empirical corroboration of postglacial sea-level rise. For each of the 21 locations, the minimum water depth (below the present sea level) needed for the details of the particular group of local-area stories to be true is calculated. This is then compared with the sea-level envelope for Australia (Lewis et al., Quaternary Science Reviews 74, 2013), and maximum and minimum ages for the most recent time that these details could have been observed are calculated. This method of dating Aboriginal stories shows that they appear to have endured since 7250–13 070 cal years BP (5300–11 120 BC). The implications of this extraordinary longevity of oral traditions are discussed, including those aspects of Aboriginal culture that ensured effective transgenerational communication and the possibility that traditions of comparable antiquity may exist in similar cultures.

Naturally, I was curious to see what was known about India, I knew off hand that there were some legends about Kerala rising from the sea, and the fact that Dwaraka, abode of Krishna, was destroyed by the sea and that recently there have been archaeological research expeditions that located traces of this famous city.

The paper cited another article dealing with sea level rises in the Asia. This one, called "Geohazards and myths: ancient memories of rapid coastal change in the Asia-Pacific region and their value to future adaptation".

This section caught my eye:

"In southern India, Tamil myths contain many allusions to ancient lands now underwater. Some myths refer to the drowning of the former cities of Madurai (Maturai) and Kapatapuram and recall that “the sea swallowed up forty-nine provinces of … land from the Pahruli River to the north bank of the Kumari River’ . Some Tamil traditions refer to the existence of Kumari Kandam, an ancient land (now submerged) off the coast of southernmost India where Tamil culture reputedly originated, a tradition that informed more recent global legends about the ‘lost continent’ of Lemuria in the Indian Ocean ."

I’d never heard of Kumari Kandam, so I looked that up. The wikipedia account states that the Lemuria hypothesis was linked to the Kumari Kandam idea, so instantly I felt that there needs to be a more careful sifting of the old sources to figure out what was more realistic. Nevertheless, there are certain old stories that incorporate a sea level rise into the plot. The wikipedia site cited one such story where the area of lost land is mentioned: a commentary on the Cilappatikaram

When I read the plot summary of the Cilappatikaram, I realised that I knew this. And the reason I knew it was because of my voracious reading of Amar Chitra Comics as a kid. I was (and am) a voracious reader. Anything that came my way. I located the story and though I’d forgotten most of it, some images (the broken anklet) were still in my memory. A testament to the power of story to record events.

Motmot Day

I have often been caught by surprise at the sudden sight of a Motmot (a blue-crowned motmot, to be precise). My eyes would idly sweep the telephone lines, or the fences or by a blue-green flash and it would often take a full moment before my brain registered the sight as a mot-mot. I first read about the bird in the context of my dayjob. Troy Murphy published a paper in the journal Behavioural Ecology in 2004, where he argued that the motmot’s twin tails acted as a pursuit deterrence signal to its predators. The bird moves the tails to and fro to warn the predator that it had been seen and so the chance of making a successful attack was less likely. This is a theme that I study with jumping spiders and Tephritid flies.

Anyway, I’d been very impressed with these birds and since Murphy’s study was done in southern Mexico, somewhere in the Yucatan, I did not even consider the possibility that there may Motmots in Veracruz. My birding days are long behind me and it takes a certain effort to remember enough details even to look it up in the bird book. But ever since I started spotting them, I became more and more fascinated with them.

The Motmot has a quiet beauty, the colours are muted but still dramatic. In a land overflowing with flashy hummingbirds and toucans, the motmot barely rates a mention. It loves the shade, slipping quietly between trees and undergrowth with all the stealth of a spy. No distinguishing call to advertise its presence, no flights of fancy.

Today, the sun came out after a bitterly cold night, and I took the camera into the garden. I had the 300 mm lens on, and I saw a few birds flitting about and I thought I might as well try to photograph a few. I want to emphasize that the whole exercise was half hearted; and I had merely the intention fo filling some time before the sun went out again.

We have a mulching corner in the garden and I noticed a buzz of activity. I sat on the grass and tried my best to get some halfway decent photos of warblers and such. After a while I grew tired and as I was getting ready to pack it up, I suddenly saw the tell tale head of a motmot sticking out behind some bushes. And then the day turned completely. For some reason the motmot kept hovering around the mulch area. Repeated sudden short flights, down to the ground and up again, always taking care to hide itself from me. I had never seen the bird for such an extended period. And then, when I was truly tiring of peering into the darkening undergrowth, I looked down and suddenly realized the reason for all that bird activity.

A whole army of army ants was flowing towards me. When army ants move, they basically decimate the insects in the area. Every insect in the vicinity desperately tries to leave, in any way possible.

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Of course all this activity attracts the attention of other insectivorous predators …such as birds, who hang around the army ants and pick off the doubly unlucky prey. I saw the motmot make a sweep down and pick off an earthworm. The birds kept at it for the whole morning.

After a while I left the scene. Imagine my surprise a few minutes later that the motmot was joined by a ‘friend’. A second one. I’d never seen two before. The day was complete. As the army ants came closer to the house, the motmots came more out into the open. Hanging around, as if they were enjoying this rare day without the need to hide.

And in the end, emboldened enough to hang out on the fountain, chatting with the Lakshmi statue in the garden.

Motion-triggered defensive display in a tephritid fly

Abstract

Interactions between prey and predators are

often mediated by signals sent by the prey. Passive signals

such as aposematic coloration and active signals such as

pursuit deterrence signals are thought to prevent attack from

predators. In true fruit flies (Diptera: Tephritidae), the

defensive wing display is called supination, and studies have

shown that supination effectively reduces the chance of

being attacked by salticid predators. In this study, we

investigated the proximal causes of supination in staged

interactions in an arena. We asked whether the movement of

the display target influences the likelihood of triggering

supination in the Mexican fruit fly Anastrepha ludens

.We tested the effect of motion on fly display in three different

ways using (1) a manually moved dead spider or beetle, (2)

live bouts with a spider and a katydid and (3) video playback

experiments where movement of the display target was

controlled. Our results show that flies are more likely to

perform supination when the display target moves. The

identity of the display target did not influence display

propensity, suggesting that the supination of flies is a gen-

eralised display behaviour against any possible threat

Motion-triggered defensive display in a tephritid fly. Available from: https://www.researchgate.net/publication/281176476_Motion-triggered_defensive_display_in_a_tephritid_fly [accessed Sep 21, 2015].

Source: Motion-triggered defensive display in a tephritid fly

Africa, Uncolonized: A Detailed Look at an Alternate Continent

What if the Black Plague had killed off almost all Europeans? Then the Reconquista never happens. Spain and Portugal don’t kickstart Europe’s colonization of other continents. And this is what Africa might have looked like. 

Source: Africa, Uncolonized: A Detailed Look at an Alternate Continent | Big Think