What did you accomplish today?

Roger A. Shrubber

Roger A. Shrubber

Well-Known Member
cannabineer said:
I cannot find a reference, but I believe conch eyes are pretty low resolution in terms of imaging. Many crabs have very finely compound eyes that image superbly. So yes the crab can probably see it in better detail.

Cuttlefish use an active optical spoofing method to disorient crabs that they are hunting - they make waves or stripes move from mantle to tentacle tips in a way that masks their slow approach to claw-bearing dinner.
Click to expand...
i was just going by physical appearance, the conch has a ring at the edge of the eye that looks very much like a camera shutter. might just be the way it looks.
eye.jpg
vectomart-camera-shutter_a-G-10359850-4986570.jpg
 
cannabineer

cannabineer

Ursus marijanus
Roger A. Shrubber said:
i was just going by physical appearance, the conch has a ring at the edge of the eye that looks very much like a camera shutter. might just be the way it looks.
View attachment 4274220
View attachment 4274218
Click to expand...
Quite possibly! I did a perfunctory search for Strombus ocular anatomy, but ~sigh~ internet.

~edit~ I did find this.

Amer. Malac. Bull. 26: 3-18 (2008 )
https://www.researchgate.net/publication/216713574_Toward_Developing_Models_to_Study_the_Disease_Ecology_and_Evolution_of_the_Eye_in_Mollusca

Excerpt. No mention of an iris, so I'm not sure.

"Gastropoda
Except for a few genera, most gastropods have a pair of
cephalic eyes. Eye placement varies among gastropod
groups, and the eye can be located at the base of cephalic
tentacles, on the tips of retractable tentacles that can with-
draw the eye, or on short stalks. Gastropod eyes range from
open pits (Fig. 3A) to closed vesicles with or without lenses.
The majority of gastropod eyes are of the closed lenticular
type (Fig. 3B), composed of cornea, lens, vitreous body, and
a cup-shaped retina (but see heteropods below). The retina
can have multiple photoreceptor types (Table 1); however,
the majority of photoreceptors near the lens are microvillous
R cells that form rhabdomeres. Other photoreceptor cells
(e.g., H cells, basal retinal neurons -BRN) are ciliary (Chase
2002). Across species, there is considerable variation in reti-
nal composition (number of cells, photoreceptor density,
organization of photoreceptors) (Hamilton 1991, Chase
2002), but the functional significance of these differences
largely is unknown and unexplored. Generally, gastropod
eyes appear to have several functions including: mediating
phototaxic behavior and locomotion, regulating daily and
seasonal activities, and, in some species, visual detection of
forms. However, the extent to which gastropod eyes have
spatial vision is still under investigation (Zieger and Meyer-
Rochow 2008) and will probably vary greatly among species.
There are several unique structures in the gastropod
sensory system. The “accessory retina”(Smith 1906) is
found in some gastropod lineages (e.g., Limacidae), which
may be involved in infrared detection (Newell and Newell
1968). Dorsal eyes appear in species of the marine slug On-
chidium Buchanan, 1800. These eyes are on papillae pro-
jecting off the dorsum of the animal (Hirasaka 1922) and are
composed of ciliary photoreceptors that may create a “rea-
sonable image”(Land 1968). See detailed descriptions in
Katagiri et al. (2002) and references therein. Probably the
most sophisticated and unique eye in the gastropods is the
scanning lenticular eye of pelagic heteropods. The retina is
not cup-shaped but forms a long strip of 3-6 cells in width,
resulting in a very narrow field of view and contains several
photoreceptor types that are unlike ciliary or rhabdomeric
receptors found in cephalic eyes of other molluscs (Land
1984). These eyes move in a systematic scanning motion,
which may be used to detect stationary objects (Land 1982).
Further work on the function of these unusual eyes is
needed. For more information on gastropod eye diversity,
there are several excellent and comprehensive reviews
(Charles 1966, Messenger 1981, Chase 2002, Zieger and
Meyer-Rochow 2008)."
 
Last edited:
GreatwhiteNorth

GreatwhiteNorth

Global Moderator
Staff member
ANC said:
Yeha man, I wanted to become a marine biologist at that stage. you should see my shell collection.
Click to expand...
I'd like to - have never been to Africa but I bet you have some kick ass shells there.

Speaking of shells I found this calcified Queen Conch in a Calusa shell mound on the SW side of Florida back in the 60's (on the coast near the Everglades) - you can clearly see where someone bashed the shell (pic #3 in the upper whorl) to break the animal's suction so it could be eaten.

Conch1.jpg Conch2.jpg Conch3.jpg
 
Chunky Stool

Chunky Stool

Well-Known Member
GreatwhiteNorth said:
I'd like to - have never been to Africa but I bet you have some kick ass shells there.

Speaking of shells I found this calcified Queen Conch in a Calusa shell mound on the SW side of Florida back in the 60's (on the coast near the Everglades) - you can clearly see where someone bashed the shell (pic #3 in the upper whorl) to break the animal's suction so it could be eaten.

View attachment 4274302 View attachment 4274304 View attachment 4274305
Click to expand...

@Gary Goodson
 
raratt

raratt

Well-Known Member
We had cone shells on Guam that could kill a person, they had a poison barb they could shoot out and stick in your hand.
 
You must log in or register to reply here.
Top