Porifera

1
Porifera

• With pores, sessile, asymetric, diploblastic
• Cells- outer pinacoderm, middle- amoebocytes and
  inner-choanocytes
• Skeleton- spicules and spongin fibres
• Water canal system
• Eg Sycon, Spongilla ( Fresh Water sponge),
  Euplectella ( Glass sponge)

2
Phylum Cnidaria
3

• 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

4

• 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

5

• 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

6

• 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

7

• 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

8

• 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)

9

• 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

10
Arthropoda

• 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

11
Mollusca ( soft body)

• 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

12
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

13
Hemichordata

• 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)

14
Chordata

• Protochordata
• Includes tunicates ( urochordates) and
  Cephalochordates
• Tunicates- notochord and nerve chord present only
  in larva
• Cephalochordates- nerve chord and notochord
  persistant

• Vertebrata
• Notochord replaced by vertebral column
• Respiration gills/lungs
• Circulation closed
• -Includes Agnatha and Gnathosomata