Caeca question, function?

[PhormictopusMan]

Hi,

If anyone can point some light on this for me I would appreciate it. I think I have a misconception of the function of the caeca system within the spider’s body. I do understand that the caecum proliferate throughout the body, the prosoma and opisthosoma as well as through the legs, and I understand that it is believed that this adaptation allows spiders to store large amounts of food for extended periods of time.

Here is where I need the help. I was under the impression that this arterial-like network was also responsible for assisting the less complex (than hemoglobin) hemolymph by directly delivering this nutrient rich solution to cells and organs, where it can be absorbed, (without being processed?) in a sort of co-operative system with the blood. Is there anything to this thought? Is this possible, or do the caeca function purely as a storage system?

Thanks for any help.

--Chris

 

[Spaceman_Spiff]

i have understood it like this:

The epithelium of the midgut consists of secretory and resorptive cells, the latter process the nutrients and pass them to the underlying tissue and the hemolymph.

So there is nothing extraordinary in the digestive system of spiders, "only" a resorptive epithelium, that secretes enzymes and resorbs and processes nutrients (sugars, fatty acids ..) and passes them to the blood (hemolymph in case of spiders) and from there to the other organs, where they are used.

The blind pouches (caeca) of the midgut are just an adaption to enlarge the resorptive surface, they are not really arteria-like and do not protrude further into the legs than to the coxae.
And i wouldn't say that spider's hemolymph is inferior, because they have no hemoglobin, it is 100% efficient in supplying the spider's organs with oxygen and nutrients, more is not needed!

I hope that helped!
greets
Bernhard

 

[PhormictopusMan]

Thank you Bernhard. I appreciate the help.

--Chris