Kai's research thread/caddisfly geekout

[Vene]

The attempt with this drawing is to show the functional complex between the lower gula of the head and the femur of the prothoracic leg. The ridge/knob on the femur rubs along the ridges on the underside of the head to produce stridulations.

I'm just going to pretend I understand what this means.  (I don't do invertebrate physiology)

[Kai]

The attempt with this drawing is to show the functional complex between the lower gula of the head and the femur of the prothoracic leg. The ridge/knob on the femur rubs along the ridges on the underside of the head to produce stridulations.

I'm just going to pretend I understand what this means.  (I don't do invertebrate physiology)

Okay, you got these ridges on the underside of the head, and you've got this nob on the front legs (you can see both of those in that drawing. These two structures create a complex (a group of characters on separate structures) that is functional (meaning it has a function) to produce sound, in the same way crickets produce sounds by rubbing wings together. The larva rubs its forelegs against the ridges and it creates a sound.

Sorry, does that make more sense? Its the most unusual stridulation (production of sound by rubbing) system I have ever heard of, and its the only such system known from caddisflies. All members of the family Hydropsychidae have stridulatory ridges, and it is supposed that all species in the family do use this for stridulation, though it has only been observed in Hydropsyche species.

[Vene]

Thanks Kai.

[Kai]

Inking of the stridulation functional complex. Probably easier to see what I was talking about.



Rough work in progress of the anal claw and abdominal plate functional complex. The two pairs of plates have backward facing spines and hairs which act as a clasp when the anal claws contract, allowing the end of the abdomen to cling flat to surfaces.

[Kai]

Also, if you look at the end of the abdomen there is a a set of setal tufts like brushes. I'm unsure what the function of these are but my hypothesis is one of three things"

1) Are used to clear debris from an area by waggling the abdomen.

2) Facilitate respiration by aiding in pulling water along the abdomen when it is wriggled dorsoventrally.

3) Aid in swimming

The last one seems most likely although all of them are plausible. The first is a pretty special purpose for such a large and obvious structure. The second is unneeded as Hydropsychids have many gills and live in streams; respiration is usually not a problem. The third makes the most sense, I think I have read it somewhere that they can swim short distances by flapping their abdomens, much like how mosquito larvae move around.

[Kai]

Illustrates how the 8th, 9th and 10th segments act together to create a clasping mechanism.

[Kai]

Final inking of the anal claw complex.



Inking of the right meso- and metathoracic legs in lateral aspect.

[Kai]

In the inked anal claw complex, you can clearly see the spine pads in relation to the anal claws. In a wholistic look (check the full drawing on previous page) the whole end of the abdomen is ovbviously recurved and flattened. This brings the entire lower surface of the 8th 9th and 10th segmets in contact with the substrate even if the rest of the body is not in contact. Essentially, Hydropsychids can hold on with nothing but their abdomen while their legs do other tasks.

In the hind legs, you can see they are longer and less stout than the forelegs (pictured previously). These are less adapted for COD (coarse organic debris) manipulation and more adapted for clinging. Also note the assesory claw that makes the tarsal claws bifid.

More thoughts about the prothoracic legs (pictured previously): in addition to being stouter, the inner surfaces are covered with thick stout setae. These help in manipulation of COD by providing friction.

Hairs on the legs are for either friction, sensation, or both.

[Kai]

(more early morning rambling follows)

Thinking about Hydropsychidae, anal claw complexes and trochantins, and external morphology.

Thinking about Caddisflies in general. Thinking about notes I took at the bar on friday.

Yes, I go to the bar to take notes. The first night I did this, an engineering professor started talking to me about his research to create a polymer which imitates the way some insects take moisture out of the air, except on a large scale. I was writing options for my thesis project at the time. Been going for 3 weeks now, bring a stack of notecards with me. Once I begin drinking the notes become scribblings and sometimes even more creative than when I was sober.

This is what I wrote down this Friday:


Thinking about Ex. Morph of Cheumatopsyche

-Anal clasping complex
-stridulating complex
-Frontoclypeus
      -Margin
-leg lengths, shapes, proportions
-antenna
-setation on legs
gill complexes
-shape of epimeral plates
-secondary claws
- setation in relation to clinging
-trochantin as spacer? collecting aid?
(why a sensory hair on the inner part of the trochantin if used for nothing)


[crude drawing of chematopsyche, lateral view]


Internal Cheumatopsyche

-tentorium (in literature)
-Gut
    -not specialized due to varied feeding habits
-heart, tracheoles, brain like lepidoptera
-In situ?
external view of head, other legs
-anat. of gills

memes are to consciousness as genes are to biology

Microsculpting on anal claws, and margins of thoracic segs
Episternum/epimeron shape/coloring SIZE?

[crude drawings of spine pads and a leg (I think?)]

Memes are the emergent genes


My uncle once told me a story about my grandfather, someone I have talked about on this forum before. They were at a bar together, just talking and drinking a beer. At some point he grabbed a napkin, and started scribbling equations down. He was always thinking about physics, even relaxing with his son in law at the bar. That was my original impulse to bring my stack of notecards to the bar with me. Now I do it because I know it works.

[Golden Applesauce]

What exactly is the anal claw?  Sorry, not to familiar with invertebrate physiology.  Is it just the last segment's pair of legs?

[Kai]

No, its actually a derived form of the tenth (terminal) segment. Over time the more basal form of the Amphismenoptera caterpillar elongated and sclerotized into these limb like appendages, but they are not true legs in the sense of the thoracic legs. They are usually termed anal prolegs.

Less terminology: The anal claws are part of the final segment of the abdomen. The whole final (tenth segment) is called the anal prolegs, because they are "not quite legs" (pro- meaning before) that are near the anus. These structures evolved from a very simple tenth segment, gaining hardened parts over time, elongating, and becoming very much like a pair of legs. Butterfly caterpillars lack them, although they are a related group, so they probably evolved only once, and then diversified from a non specialized form. In this particular group of caddisflies the prolegs are very long, but in other groups they are very reduced, only a set of simple claws.

[Bebek Sincap Ratatosk]

What exactly is the anal claw? 

A special limb for teh surprise buttsecks.

[Mesozoic Mister Nigel]

What exactly is the anal claw? 

A special limb for teh surprise buttsecks.

Damn, I need me one of those!

[Kai]

What exactly is the anal claw?

A special limb for teh surprise buttsecks.

Only if its children buttsecksing adults.

Only the larvae have anal prolegs.

[Mesozoic Mister Nigel]

What exactly is the anal claw?

A special limb for teh surprise buttsecks.

Only if its children buttsecksing adults.

Only the larvae have anal prolegs.