Editing Rotifer (section)

=== Digestive system ===
[[File:Bdelloid.JPG|thumb|upright=1.5|right|Scanning electron micrographs showing morphological variation of bdelloid rotifers and their jaws.]]

{{Multiple image
| direction = vertical
| align = right
| width = 220
| header = Rotifer colonies
| image1 = 20100708 colonial rotifer Conochilius.JPG
| caption1 = Colonial rotifers, tentatively identified as ''Conochilus''. The colony is less than 1 mm in diameter, but visible to the naked eye.
| image2 = Sinantheria-socialis.jpg
| caption2 = Colony of ''Sinantheria socialis'' on an ''[[Elodea densa]]'' leaf. Note heart-shaped corona of individuals.
}}

The coronal cilia create a current that sweeps food into the mouth. The mouth opens into a characteristic chewing [[pharynx]] (called the ''mastax''), sometimes via a ciliated tube, and sometimes directly. The pharynx has a powerful muscular wall and contains tiny, calcified, jaw-like structures called ''trophi'', which are the only fossilizable parts of a rotifer. The shape of the trophi varies between different species, depending partly on the nature of their diet. In suspension feeders, the trophi are covered in grinding ridges, while in more actively carnivorous species, they may be shaped like [[forceps]] to help bite into prey. In some [[ectoparasite|ectoparasitic]] rotifers, the mastax is adapted to grip onto the host, although, in others, the foot performs this function instead.<ref name=IZ/>

Behind the mastax lies an [[oesophagus]], which opens into a [[stomach]] where most of the digestion and absorption occurs. The stomach opens into a short [[intestine]] that terminates in a [[cloaca]] on the posterior dorsal surface of the animal. Up to seven [[salivary gland]]s are present in some species, emptying to the mouth in front of the oesophagus, while the stomach is associated with two gastric glands that produce [[digestive enzyme]]s.<ref name=IZ/>

A pair of [[protonephridium|protonephridia]] open into a bladder that drains into the cloaca. These organs expel water from the body, helping to maintain [[osmoregulation|osmotic balance]].<ref name=IZ/>

{{Multiple image
| caption_align = center
| direction = horizontal
| align = left
| header = Individual rotifers
| total_width = 660
| image1 = Philodina rugosa 756859.jpg
| caption1 = ''Philodina rugosa''
| image2 = Mikrofoto.de-Raedertier Ptygura pilula 2.jpg
| caption2 = ''Ptygura pilula''
| image3 = Mikrofoto.de-Brachionus quadridentatus 6.jpg
| caption3 = ''[[Brachionus|Brachionus quadridentatus]]''
}}
{{clear}}