Mesozoa
Multicellular endoparasites, body composed of outer cell layer called syncytium enclosing reproductive cells Locomotion by cilia No tissue, organ or cavities are present Life cycle composed of alternation of sexual and asexual generation Endoparasite in sea star, annelids and in other marine invertebrates They have been placed between protozoa and Porifera Shows affinities with protozoa, Coelenterata and with Platyhelminthes
Ctenophora
Ctenophora means comb bearer refers to the locomotory comb like plates on the body Transparent gelatinous unsegmented body without nematocysts but has lasso cells Skeletal, excretory, circulatory and respiratory system are absent Development include metamorphosis with cydippid larva stage Asexual reproduction absent Economic importance: consume large number of oyster larvae at spawning time Shows affinities with Coelenterata and with Platyhelminthes They have been placed in Coelenterata
Rhynchocoela
Rhynchocoela means proboscis cavity. They have remarkable proboscis aperture used in capturing pray Also called ribbon worms due to long dorsoventraly flattened body Excretory system consist of localized tubules ending in flame cells Hermaphrodite, asexual reproduction by fragmentation Nervous system include four lobed brain Shows affinities with vertebrates, chordates and with Platyhelminthes
Page No. 1 of 5 Minor Phyla Entoprocta
Entoprocta refers to the location of anus along with mouth within the crown of distal tentacles Individual consist of calyx, stalk and stolon Digestive tube is U-shaped and ciliated Retractor muscles are present Excretion occur by protonephridia ending in flame bulb, single nephridiophore near mouth Development includes a free swimming ciliated larva which attaches to grow into adult Shows affinities with Ectoprocta and with rotifera
Acanthocephala
Endoparasites with a retractile proboscis armed with hooks Excretory organs are protonephridia with modified flame cells Sensory papillae are present on the proboscis Egg developed into embryo inside the body of female Shows affinities with Nemathelminthes, Aschelminthes and with Platyhelminthes
Nematomorpha
Body is hair like, unsegmented and triploblastic Digestive tracts degenerate in adults Development include larva with peculiar boring organ, enters an insect host and grow to adult stage before returning back to water Shows affinities with Aschelminthes
Rotifera
Rotifera means wheel bearers refers to the rapid movement of cilia in a regular sequence on one or more disc like lobes of head producing the appearance of a rotating wheel Fresh water animal rarely marine Body unsegmented divisible into three parts head, trunk and tail Head modified into retractile ciliated corona for locomotion and food collection Tail is mobile containing the pedal glands
Page No. 2 of 5 Minor Phyla Digestive system with a modified muscular grinding pharynx bearing internal jaws Excretion is by protonephridia tubes with flame cells ending in cloaca Sense organs are as eye spot Shows affinities with Arthropoda, Nematoda and with Platyhelminthes
Gastrotricha
Gastrotricha means stomach hairs refers to the ventral ciliation of the gastrotriches Cuticle forms the scales, spines and bristles Freshwater forms are with only parthenogenic females while marine forms are hermaphrodite Eggs are large Excretion is by protonephridia tubes with flame cells Shows affinities with Rotifera and with Nematoda
Kinorhyncha
Kinorhyncha means movement snout refers to the withdrawal of head proboscis into neck Body consist 13-14 rings which are strongly cuticulized Head is retractile bear circlet of hook around a terminal mouth on a short proboscis Body surface is devoid cilia but provided with spines and bristles Excretion is by protonephridia tubes with flame bulb Development include larval stages and metamorphosis Shows affinities with Arthropoda, Nematoda and with Platyhelminthes
Bryozoa
Bryozoa means moss animal refers to the superficial resemblance to a colony of moss Colonies found attached with stones, shell and other objects in shallow water Zooids of colony connect together by an organic substance and shows polymorphism Each zooid secrete a protective cup shaped exoskeleton Calles zoecium The anterior end of zooid form a horseshoe shaped structure called lopophore bearing a series of slender, ciliated, hollow tentacles Development take place in a special brood chamber and include free swimming ciliated larva which settle down and metamorphoses into the adult zooid from which colony is form by budding
Page No. 3 of 5 Minor Phyla