Sunday, July 31, 2011

A change of diet

Cyperus alternifolius - a relative of the papyrus
A tiny egg is visible at 2 O'clock
The leaves are eaten and curled. Inside a curl was a pupa.
The adult emerges one morning at ten end of December
The wings are inflated and the skipper seeks a vertical surface
The vertical surface is what it likes

The Giant Red-eye (Gangara thyrsis) is a well known skipper that breeds on a range of palms. Strangely, it seems like one female decided to lay its eggs (December 2009) on Cyperus a member of the Cyperaceae, rather distant from the palms. I have kept a regular lookout for a repeat of this phenomenon and it has not happened and it seems like a case of accidental oviposition. The mistake however does not seem to have had an ill effect on the young.

Further reading

Saturday, July 30, 2011

Ocelli in hindsight

Forest calotes sleeping
About a year ago I was musing over the spots on butterflies and most of it was about getting away from predators. On a recent visit to Rishi Valley, thanks to Dr Santharam, I spotted a female Calotes versicolor. Interestingly it had on the back of its head, two ocelli (false eyes, not to be confused with the functional simple eyes in insects). My impression was that this feature was more prominent in the Forest Calotes (C. rouxii).

Some years ago, I spotted the forest calotes on the right at night. I was not aware of the sleeping habit of these lizards until it was pointed out to by Saleem Hameed. They apparently always choose  the end of an overhanging tendril or branch which they clasp and roost. In the photograph of a roosting rouxii you can see the two eyespots on the back of the head.

A female C. versicolor, possibly gravid
The Rishi Valley Calotes appears to be a gravid female and has two ocelli. Perhaps I have not paid enough attention to this but the phenomenon of ocelli in more predatory species is apparently more widespread. It is also found a few falcons, hawks and owls. The white spots behind the ear of the tiger have also been pointed out as being similar.



Further reading

Saturday, July 16, 2011

Invaders on the tree trunk

Herennia with a male at left
Why did the fly fly
because the spider spied 'er


On a visit to the Kaveri riverside, I spotted this spider on the trunk of a Terminalia arjuna. It was only muxh later that I learnt about its identity. It seems to be Herennia possibly H. multipuncta. Like many successful creatures it has been termed as an "invasive", apparently because it has been found rather unexpectedly on many islands across Asia. It seemed rather odd, for I had never seen it before and one generally expects "invasives" to be more ubiquitous. Anyway, "invasives" appear to be one of those buzzwords invented by scientists to get funding behind their work and for a recent turn of events on the "science and politics" behind the term - do check out this essay. Anyway, the female of our spider is the large one with a strange disc with pores while the tiny orange one at the left is the male. It takes a while to realize that it is an orb-weaver and are in the same family as the Nephila wood spiders, the orb is actually placed close to the tree trunk in tight circle and presumably targets small bark living insects. The orb itself is constructed so that it does not touch the trunk, but this was not readily apparent. The male at the left appears to be unmated - as apparently those that mate, sever their pedipalps - blocking the female genital opening to ensure paternity. These eunuch males cannot mate again but continue to stay beside the females.
Further reading

Wednesday, July 13, 2011

Prying levers

F-W-E
The levers three
each in turn in the centre be


A school mnemonic to remember the three orders of levers (with the fulcrum, weight and effort at the centre). 
Muscle schematic

In biological systems, the third order lever is the most often seen system. On a recent trip a friend of mine pointed out the foraging technique used by Asian Pied Starlings - they always pierced the soft soil and then were opening apart their bill to uncover prey. Some subsequent research showed that this prying or gaping action of starlings was well documented from an anatomical perspective but rarely recorded in behavioural studies. Another Indian bird that is well known for prying is the Hoopoe. All these birds have better developed muscles to open apart the bill. However some species have the lower mandible processes extending further back to give extra leverage.


It is a better known fact that birds can move their upper mandible, to a greater degree in some cases as in the skimmers and parrots.
Huia skulls

Lower mandible depressor muscles and the extended process at the back of the mandible are (were ?) particularly pronounced in the now extinct Huia. This bird had an extraordinary sexual dimorphism in the bill shape (although the bony parts are similar and the difference in length largely accounted for by the rhamphotheca). It appears that a downward curve is quite helpful when depressors are well developed. The Huia also had a cavity at the back of the skull to accomodate the muscles used to open apart the beak. Interestlingly a fossil bird with similar adaptations was described in 2005 by Gerald Mayr. Although the case of the Huia was never mentioned in that study, he notes that none of the skulls he examined (including that of the Pied Myna) had as long a process extending backward.



References



Saturday, July 9, 2011

The endless miles to read

Hidden away between the Jungle Books of Rudyard Kipling is a lovely story titled "The Miracle of Puran Bhagat". Sir Purun Das KCIE however came to mind again while reading Jon Krakauer's Into the Wild (1996), which I have just read many years after it was first published. A very impressive and moving work that everyone who thinks about themselves and the environment will appreciate. Economics and ecology, both words derived from the same roots (oikos for "home"), are remarkably disparate and the connections and disconnections resulting from mixing the two should make anyone think about the compromises we make. Even though few would be against conserving the environment, the debates of left versus right, top-down versus bottom-up are enough to suggest that the least contradictions are found in the anarcho-primitivist position. Unfortunately, it is a position that very few have managed to attempt living without getting into the situation of Chris McCandless or Theodore Kazynski. And it seems like one has to also read Tolstoy and Thoreau and so much more to understand the origins of the various viewpoints. It would be great if there was an accessible classification of the various philosophical underpinnings of conservation to make up for the rather superficial and misused blanket labels widely in use.
"When the first handful of Norwegians showed up on the shores of Iceland in the ninth century, the papar (Irish monks) decided the country had become too crowded-even though it was still all but uninhabited. The monk's response was to climb into their curraghs and row off towards Greenland. They were drawn across the storm-racked ocean, drawn west past the edge of the known world, by nothing more than a hunger of the spirit, a yearning of such queer intensity that it beggars the modern imagination." Into the Wild p. 97
"waiting for father" by R A Sterndale - this was about a family of bears waiting for their father that was killed. The next day the mother bear was also killed. Sterndale's work was an inspiration for Kipling.


PS: It seems like this site lets me post notes but does not let me post responses to comments!