Inbiological morphology, atyphlosole is an internal fold of theintestine or intestine inner wall.[1] Typhlosoles occur inbivalve mollusks,lampreys and someannelids andechinoderms.
Inearthworms, it is a dorsal flap of the intestine that runs along most of its length, effectively forming a tube within a tube, and increasing the absorption area by that of its inner surface. Its function is to increase intestine surface area for more efficient absorption of digested nutrients. In differentearthworm families, the typhlosole appears to have multiple origins. TheLumbricidae, for example, have a typhlosole which is an infolding of all layers of the intestine wall, whereas in some other families (e.g.Megascolecidae), it is an infolding of only the inner layer, and in many earthworms it is absent.
In shipworms, the typhlosole is the organ where thelignin in wood are digested bysymbiont bacteria of the "Alteromonas-like sub-group".[2]
