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Porifera
• With pores, sessile, asymetric, diploblastic
• Cells- outer pinacoderm, middleamoebocytes and inner-choanocytes
• Skeleton- spicules and spongin fibres
• Water canal system
• Eg: Sycon, Spongilla ( Fresh Water
sponge), Euplectella ( Glass sponge)
Phylum Cnidaria
General Characteristics
• They are radially symmetrical; oral
end terminates in a mouth
surrounded by tentacles.
• They have 2 tissue layers
• Outer layer of cells - the
epidermis
• Inner gastrodermis, which
lines the gut cavity or
gastrovascular cavity
(gastrodermis secretes digestive
juices into the gastrovascular
cavity)
• In between these tissue layers is a
noncellular jelly-like material called
mesoglea
Cnidarian Body Plans
Polyp form
• Tubular body, with the mouth directed upward.
• Around the mouth are a whorl of feeding tentacles.
• Only have a small amount of mesoglea
• Sessile
Medusa form
• Bell-shaped or umbrella shaped body, with the mouth is directed downward.
• Small tentacles,
directed downward.
• Possess a large
amount of
mesoglea
• Motile, move by
weak contractions
of body
Nutrition
• Cnidarians are carnivores with hydras and corals consuming
plankton and some of the sea anenomes consuming small fishes
• They use they tentacles to capture prey and direct it toward the
mouth so that it can be digested in the gastrovascular cavity via
secretions from gland cells (extracellular digestion); some food is
phagocytized by special cells and digestion occurs intracellularly
• The gastrovascular cavity exists as 1 opening for food intake and
the elimination of waste
• There is no system of internal transport, gas exchange or
excretion; all these processes take place via diffusion
- Alternation of generation
- Mouth or hypotostome present
Ctenophora: Comb jellies
- diploblastic, tissue level organisation
- An outer epidermis, mesoglea with amoebocytes, and
- An inner gastrodermis
- Colloblasts- on epidermis of tentacles- for prey capture
- locomotion- cilia with comb plates for nutrition
- Eg: Ctenoplana Hormephora
Platyhelminthes: Flat worms
- unsegmented, bilateral symmetry, triploblastic
- Acoelomate, organ system level of organisation
- Suckers and hooks for holding the intestine of host
- Incomplete gun – only mouth present, no anus
- Excretion- Flame cells
- Regeneration capacity high in Planarians
- Eg; Taenia solium, Fasciola hepatica
NEMATHELMINTHES -
Round worms / thread worms
Bilateral symmetry, Triploblastic , pseudo coelomate
Alimentary canal- complete with muscular pharynx
No respiratory and circulatory system
muscles- Circular and longitudinal
Sex- seperates; male shorter than female
Fertilisation – internal
- Ascaris, Wuchereria, Ancylostoma ( Hook worm)
Annilida : Annullus: little ring
-
Triploblastic, bilateral symmetry, coelomate
Metamerism
Muscles- longitudinal and circular
Digestion – complete
Excretion- nephridia; circulation- closed
Some are bisexual
Development- indirect through Trocophore larva
Eg; Pheritima, Tubifex ( blood worm), Neries
Arthropoda
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Body – Head, thorax and abdomen
Jointed appendages, antennae, eyes ( ommatidia) and statocysts
Digestive system is complete
Chitin ; undergoes Ecdysis/ moulting
Respiration- Gills/ trachea/ Book lungs/ / Book Gills
Excretion- Malphigian tubules/ nephridia
Fertilisation- internal , oviparous
Apis , Bombyx, Laccifer, Anopheles, culex, locusts, Limulus
Mollusca ( soft body)
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Body- Head, Visceral mass , muscular foot
Radula- rasping organ
Body wall – with mantle- secretes shell
Digestion – complete; excretion- nephridia
Unisexual, external fertilisation, oviparous
Indirect development- Veliger, trocophore
and Golchidium larvae
Echinodermata
• Endoskeleton- calcarious plates with spines
• larvae- bilateral sym and adults- radial sym
• Water vascular system with tube feet,
radial canals– excretion, circulation
• High regeneration capacity
• development- indirect: Plateus, bipinnaria
and auricularia
Hemichordata
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Body- Proboscis, collar and trunk
proboscis- Ciliated for collecting food
Mouth- between proboscis and collar
Stomochord- similar to notochord
Excretion- proboscis gland
Reproduction- sexual, dev- indirect (
tornaria)
Chordata
• Protochordata
• Includes tunicates (
urochordates) and
Cephalochordates
• Tunicates- notochord
and nerve chord
present only in larva
• Cephalochordatesnerve chord and
notochord persistant
• Vertebrata
• Notochord replaced by
vertebral column
• Respiration –
gills/lungs
• Circulation – closed
• -Includes Agnatha and
Gnathosomata