Chitons
Sea snails
Sea slugs or
Nudibranchs
Octopus
Squid
PHYLUM: BRYOZOA
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PHYLUM: CHORDATA
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Look like seaweeds, corals or hydroids
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Build colonies
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Include all Vertebrate classes
All have similar features in larval
stage = tadpole like
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Dorsal Nerve chord
Stiff dorsal rod (notochord)
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Moss or lace animals
Bilateral symmetry
Pharyngeal gill slits
Sea squirts
 Individual or colonial
 Cellulose casing = tunic
PHYLUM: ECHINODERMATA
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Spiny skin
Pentaradial (5 part ) symmetry
Endoskeleton ( on the inside)
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Tubefeet
Sea urchin
Starfish
Sea cucumber
Brittle star
Feather star
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Two Oceans Aquarium Volunteer Manual – Module 3 – INVERTEBRATES
Meaning of Important biological terms
1. Types of Feeding Methods
Filter feeders – An animal that uses some body part to strain very
small animals or plants (plankton ) from water
Herbivore- An animal that eats plants or algae
Detritus feeder – animal that feeds on dead material (detritus). This is
mainly plant material.
Carnivores – An animal that eats other animals. There are two
methods by which they acquire their prey viz. Hunting or scavenging
for dead remains of animals
Predators – Animals which catches, kills and eats its prey.
Scavengers – Opportunistic animals that will attack and eat prey that are
injured or dead.
Omnivores – Animals that eat both plant and animal material.
2. Types of body shapes = Symmetry
Symmetry in biology is the balanced distribution of duplicate body parts or shapes. The
body plans of most multicellular organisms exhibit some form of symmetry.
Asymmetrical – No symmetry.
A small number of animals show no symmetry (are asymmetric).
Radial Symmetry
The arrangement of the body of an animal in which parts are arranged around a
single central point.
Most animals with a circular body plan are radially symmetrical e.g. sea
anemones(see fig 11)
Central point
Fig 11. Showing radial symmetry of sea anemone
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Bilateral Symmetry
The body of the animal can be divided into two equal halves.
The left half is exactly the same shape as the right. It has a
definite front and back, and a left and right side e.g. crabs.
Quick review
1. Match the term with the correct explanation.
Column A
Column B
Invertebrates
Describes the body plan of the
animal
Symmetry
Animals which eats small
microscopic animals or plants
Filterfeeder
Animals which eats plants
Carnivore
Animal where the left side is
exactly the same as the right side
Bilateral symmetry
Animals
animals
Radial symmetry
Animals with a circular body plan
Herbivore
Animals without a backbone
which
eats
other
2.
In the table below number the names given from highest classification to lowest
classification.
Genus
Class
Order
Phylum
Family
Species
3. Why is classification so important in the naming of animals?
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Two Oceans Aquarium Volunteer Manual – Module 3 – INVERTEBRATES
PHYLUM: PORIFERA
(pori = pores and fera = bearer)

SPONGES
CHARACTERISTICS
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Has pores
No upper or lower side, no front or back - grows in any direction.
No true tissues or organs present.
All members are sessile ( attached) and exhibit little detectable movement.
No symmetry = asymmetrical
Habitat
Sponges prefer to grow on a solid base such as rocks in the infratidal/intertidal zone where they
may be exposed at a very low tide. They are found under rock ledges and in caves away from
direct sunlight. Many are found sub-tidally along the South African coast.
Description
Sponges are the least animallike of all marine animals.
They look like bits of
coloured bath sponge. They
can be red, orange, blue,
purple, brown or grey in
colour and are easily
recognised by many small
holes in their surface. The
body shape is variable, e.g.
Flagella beat to create water movement
for feeding
Living Shores: Figure 175
Did you know?
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A sponge has a three-dimensional scaffolding or lattice that
supports the jelly-like body.
This lattice is formed of little spikes of silica, calcium carbonate
or a tough fibre called spongin. A natural bath sponge is the
skeletal remains of a sponge supported by spongin.
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flat encrusting, tubular, globular.
Feeding
They obtain their food by filtering particles of organic matter and microorganisms e.g. bacteria
out of the water.
Sponges are thus very important ecologically as they filter the shallow coastal water.
Predators
Animals such as flat worms and bristle-worms eat some sponges.
The varying bright colours of the sponges may act as a warning to predators they are unpalatable
(the spicules may act as an irritant).
Sponge Bob and his friends are characters in a cartoon called
Sponge Bob Square Pants . Sponge Bob walks. He talks. He
flips perfect Krabby patties.
Of course real sponges can’t do any of that – they don’t have
eyes, lungs, a heart, or other organs.
A sponge is made up of a collection of individual cells that
work together. That is why a sponge can grow back together
after being broken into small pieces, which sometimes
happens to sponge Bob.
Chances are the sponges you clean with – the kind that look
like Sponge Bob – aren’t from the sea but are made from a
material called cellulose.
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Two Oceans Aquarium Volunteer Manual – Module 3 – INVERTEBRATES