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P Kamptozoa (Entoprocta)

F
Loxostomatidae



 

Kamptozoa

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Overview & Classification


Ecology


Habitat


Associations


Biogeographic Distribution


Physical Characteristics


External Features


Internal Features


Biology & Behaviour


Reproduction & Development


Nutrition, Transport & Excretion


Predation & Disease


Climate Change


Evolution & Systematics


Diversity & Identification


Phylogeny


Glossary


Acknowledgments, References & Additional Notes

Biology & Behaviour - Nutrition, Transport & Excretion

Filter feeding is used by kamptozoans by means of its tentacular crown and cilliated tentacles, trapping small organic food particles with their numerous cilia, and larger microscopic organisms with unique lime-twig glands secreting threads of glue within the crown. The individual zooids can also ‘nod’ by bending its stalk, to capture prey otherwise missed if calyx position is maintained.

As commensals, kamptozoans use the water currents created by the bryozoan zooids to capture food. The lateral cilia on the tentacles also create currents which send particles through the base of the tentacular crown and out the top of the crown. Suspended particles are then trapped by these lateral cilia and transferred to frontal cilia on the inside surface of the tentacles. These cilia beat downwards toward the atrium, hence the naming of this system as a downstream collecting system, as opposed to the upstream collecting system of bryozoans, which transfer food from the base of the tentacle to the tip, and deposit the particle into the mouth by moving the tentacle. Food particles are then carried along a groove in the atrium and into the mouth. This groove, in conjunction with the tall conspicuous anal cone distinctive of loxosomatids, ensures that non-ingested particles are not mixed with waste particles coming from the anus.

The stomach is very large, and as no phagocytosis has been demonstrated, this is presumably the area of enzyme secretion and breakdown of particles. The intestine, with abundant microvilli on the gastrodermis, is thought to be the main area of nutrient absorption.

The whole of the gastric system can be isolated by two circular sphincters, located at the mouth and at the anus of the animal.

The U-shaped gut taking up most of the organism, nutrients are transported to all parts of the calyx via diffusion through the tissues. Transport is achieved in the stalk in some species by the contraction of cells of the star-shaped organ, situated at the junction between the stalk and calyx.

Because if its small size, effective gas transport can also be assured by diffusion across the entire body surface.


Deleterious materials are excreted from entoprocts by protonephridia, usually paired and found in the atrium. These are terminal cells with multiciliated flame cells attached to it, which create a current for excess waste to be expelled from the body without being reabsorbed.

Classification

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