A larvae, a caterpillar and a jumper.

[P_T]

I thought it was a stick or part of the leaf, turned out it's a larvae of some sort.


I don't know what species this caterpillar belongs to.


I wouldn't have posted this one if it looked the same as the other jumper photos I've posted but this one's a bit blueish.

[Cyclops]

Nice pics, and of course I love the spider!
Looks to have just molted too!

I think the first one is one of those looper caterpillars,( are called Inch worms in the states?) so some kind of Moth larvae.

[P_T]

Looks to have just molted too!

Thanks mate! that would explain the lack of hair.

[Cyclops]

Looks to have just molted too!

Thanks mate! that would explain the lack of hair.

Yea plus they look very translucent when just molted, almost like theyre made of jelly. Then they harden,go darker and the colours look more vivid than before(I keep tarantulas and I have witnessed this first hand)

[rjlittlefield]

that would explain the lack of hair

I'm under the impression that all the hair it's going to have will be present even right after molting. In other words, the hairs don't grow out of the cuticle between molts, but rather are fully formed when the molt occurs.

Is that not correct?

--Rik

[Cyclops]

Rik, the hairs on its legs, called the trichobotria,are actually sensory organs linked to the central nervous system of spiders and as such I believe they are fully formed with each molt rather than being left behind in each exuvia each time it molts. That is, the spider molts with them already intact, as far as I know. But when P_T mentioned hairs I was set into thinking of tarantulas which have very hairy abdomens which are shed with the exuvia-they are defensive hairs in many ground living species. (Which explains why they are more colourful after each molt) I dont know that tarantulas have the trichobotriae though.

[rjlittlefield]

Ah, I love it how a little side comment can provoke so much investigation!

Last Christmas, I think it was, Santa brought me a copy of "Biology of Spiders" by Rainer F. Foelix. I haven't had time to read the whole thing -- and even if I had, I wouldn't remember most of it! But it's great fun to go read portions when questions like this come up.

First, on the subject of sensory "hairs", here's what Foelix has to say (pp 26-29).

All leg segments are covered with various sensory hairs, discussed here only briefly (for details see chapter 4). Most of these sensilla are movable, articulated setae, or bristles, which function as mechanoreceptors (touch, vibration). Each leg receptor is associated with several primary sensory cells, and consequently, sensory nerves are built up by thousands of separate sensory fibers.

A particularly interesting type of sensillum is the trichobothrium, a very thin hair set almost at a right angle to the leg axis. Originally the trichobothria were thought to represent hearing organs, but later they were considered "touch-at-a-distance" receptors, because they react to air currents and low-frequency air vibrations.
...
In addition to the mechanosensitive sensilla, we also find chemosensitive hairs on all distal leg segments. These hairs are characterized by an open tip in which several nerve fibers are exposed directly to the environment. It has been known for a long time that spiders can test the chemical quality of a substrate merely by probing it with the tips of their legs.

The book's Fig.26 is captioned in part "Leg receptors. (a) Lateral view of a tarsus in Agelena. Most sensilla are simple tactile hairs (T), but a few slender trichobothria (Tr) and chemosensitive hairs (Ch) can also be seen."

Cool! I did not know about the trichobothria or chemosensitive hairs.

About the molting process, he writes (pages 226-228)

In a strict sense molting comprises two different processes: (1) apolysis, the separation of the old cuticle from the hypodermal cells; and (2) ecdysis, the shedding of the entire old skin (exuvium), which corresponds to what most people think of as molting. Apolysis precedes ecdysis by about one week.

Cellular Events

The epidermal cells secrete certain enzymes (chitinases and proteases) into the gap that develops between the epithelium and the cuticle, the exuvial space. These enzymes gradually dissolve the endocuticle but attack neither the exocuticle nor the nerve fibers associated with the sensory hairs.
...
It seems particularly interesting that the sensory hairs remain functional during most of the molting process. The reason is that the innervation of the old sensilla is maintained while the new hairs develop on the surface of the hypodermis. The long dendrites innervating each "old" hair sensillum lie freely in the exuvial space and become wrapped by a sheath cell. This cell starts to secrete cuticle on its outside, thus producing the new hair shaft. Another sheath cell is responsible for the formation of the socket in which the hair shaft is articulated. About 24 hours before ecdysis all new hair sensilla are completely developed, and only then is the continuity between the old and the new sensory hair broken. When the exuvium is cast off, only the tips of the dendrites are lost, and the new hair sensilla are thus functional immediately after molting.

A fascinating process! I always wondered how that works.

Thanks for the info and tickle, guys!

--Rik

[Cyclops]

Fascinating things spiders huh Rik! BTW that book has been on my wishlist for some time. Maybe one day...