Download Module 4 : Marine Invertebrates

Module 4 :
Marine Invertebrates
TABLE OF CONTENTS
Invertebrates
2
Introduction
2
Meaning of Important Biological terms
7
Phylum Porifera
9
Phylum Cnidaria (Coelenterata)
11
Phylum Platyhelminthes
21
Phylum Sipunculida
23
Phylum Annelida
24
Phylum Arthropoda
29
Phylum Bryozoa
42
Phylum Mollusca
43
Phylum Echinodermata
60
Phylum Chordata
68
Two Oceans Microscope
70
Key Concepts
Underline or highlight the concepts as you read through the notes.
1.
2.
3.
4.
5.
Why is classification important?
Name of Phylum and main characteristics.
Methods of feeding
Different kinds of symmetry and the advantages of each.
Identify species found at touch pool and microscope
o Interesting facts about the species
o method of feeding
o habitat,
o parts of the animal and its function
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
1
What is an Invertebrate?
An invertebrate is an animal without a backbone (vertebral column). The majority of animals in
the animal kingdom are invertebrates.
INTRODUCTION
ORGANISMS: THEIR VARIETY AND CLASSIFICATION
Imagine having over a million living animals around without names, which are not grouped in any
way. If this were the case it would be impossible to remember the details of the organisms.
If they were systematically ordered, one would only need to remember the basic construction
pattern and the common characteristics of each group to make sense of the animals.
Why is classification important?
 helps us enormously to identify the animal or plant and give it an acceptable scientific
name
 to work out the relationships between the different groups of animals and plants
 to enable scientists to communicate and share information about organisms
 to show interesting evolutionary phenomena
 to help understand patterns of development of life on earth.
The science of classifying organisms, whether plants or animals into groups, is known as
taxonomy.
CREATING ORDER OF THE LIVING WORLD
2

Certain animals have certain characteristics in common and they are grouped together in a
hierarchical system (from many to few characteristics)

The highest ranks in the animal kingdom are called PHYLA (singular: phylum). This rank is
called a DIVISION in the plant kingdom.

Because of ever increasing differences in the external and internal structures between
organisms, they are further grouped into lower ranks that are called CLASS, ORDER,
FAMILY, GENUS AND SPECIES in ‘descending’ order.

For instance, a species is a specific animal, which belongs to a genus (of very similar
animals), which belongs to a family (of very similar animals), etc.

In the table below a comparison is made between the way that animals are classified and
the way that supermarket products such as coffee is classified and arranged on the
supermarket shelves.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
Phylum

Class

Order

Family

Genus

Specie
ANIMAL KINGDOM
NON-LIVING WORLD
Arthropoda

Crustacea

Decapoda

Grapsidae

Grapsus

Grapsus fourmanoiri
(Green rock crab)
Beverages

Coffee

Instant Coffee

Pure Instant coffee

Nescafé

Nescafé classic
NAMES
The strange sounding names of living organisms are derived from Greek or Latin and are
continuously given to organisms as new species are discovered and technology developed. They
describe a common, outstanding characteristic of each phylum, class, order, family, genus and
species.
For example the phylum Arthropoda comes from the Greek arthron - joint and podos - foot and
all animals belonging to this phylum have jointed legs.
GENUS and SPECIES names
It is by these two names that all the different recorded organisms on earth are distinguished from
each other.
In scientific papers and books these two names are usually printed in italics, first the (Genus)
generic name (with capital letter) and then the species name with small letter e.g. Grapsus
fourmanoiri (Green rock crab).
Below is a key to indicate animals which might be found at the Touch pool and Microscope.
KEY
Touch Pool
Microscope


Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
3
The table below illustrates PHYLA that contains examples of marine invertebrate animals
PHYLUM: PORIFERA



Has pores
Skeleton made of spicules
Asymmetrical (no symmetry)

No tissues or organs
Sponges
PHYLUM: CNIDARIA



Stinging cells (nematocysts)
Hollow gut with a single opening

Hydrostatic skeleton

Radially symmetrical
2 body forms: polyp and medusa
Anemones and Zoanthids
Hard Corals
Jellies
Soft Corals and Sea Fans
Hydroids
PHYLUM: PLATYHELMINTHES



Flat worms
Bilateral symmetry


Not segmented

4
PHYLUM: SIPUNCULIDA
Bilateral symmetry

Flatworms
Bluebottles
Not segmented
Introvert and trunk
Eye spots
Peanut worm
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
PHYLUM: ANNELIDA

Ring – like external bands - segmented

Bilateral symmetry


Bristle worms
Jaws or modified mouth parts
Free living worms
Sedentary (live in tubes) worms
PHYLUM: ARTHROPODA


Jointed limbs
Exoskeleton made of chitin

Moults to grow bigger

Bilateral symmetry
Sea spider
PHYLUM: ARTHROPODA – Subphylum: Crustacea

Exoskeleton form a shield = carapace

2 pairs of antennae
Isopods and Amphipods
Hermit crabs
True crabs
Barnacles
Shrimps, Lobsters, Prawns
PHYLUM: MOLLUSCA



Limpets
Soft body
Bilateral symmetry
Most examples have a shell
Bivalves
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
5
Chitons
Sea snails
Sea slugs or
Nudibranchs
Octopus
Squid
PHYLUM: BRYOZOA

PHYLUM: CHORDATA

Look like seaweeds, corals or hydroids


Build colonies

Include all Vertebrate classes
All have similar features in larval
stage = tadpole like


Dorsal Nerve chord
Stiff dorsal rod (notochord)

Moss or lace animals
Bilateral symmetry
Pharyngeal gill slits
Sea squirts
 Individual or colonial
 Cellulose casing = tunic
PHYLUM: ECHINODERMATA



Spiny skin
Pentaradial (5 part ) symmetry
Endoskeleton ( on the inside)

Tubefeet
Sea urchin
Starfish
Sea cucumber
Brittle star
Feather star
6
Two Oceans Aquarium Volunteer Manual – Module 4 – 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 or detritivore – 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
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
7
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.
Colonial- descriptive of organisms produced asexually which remain
associated with each other – may retain tissue contact.
Also describes sexually produced organisms that form semi
permanent aggregations in space
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?
8
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
PHYLUM: PORIFERA
(pori = pores and fera = bearer)

SPONGES
CHARACTERISTICS





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?


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.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
9
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.
10
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
PHYLUM: CNIDARIA (COELENTERATA)
Cnida = nettle (stinging)
CHARACTERISTICS

Multicellular animals.

Body is essentially a sac with two cell layers in the body wall and a single opening, the
mouth.

The mouth is surrounded by tentacles, which contain stinging cells (nematocysts)
that assist in capturing the prey.

They are built on a circular body plan and are radially symmetrical.

There are two common forms: (also see next section figure 180 A)
o the polyp which attaches itself to the rock for example the sea anemone and
o the medusa which is bell shaped and floats mouth downwards in the water
for example the jellyfish.
Living Shores: Figure 180 A
Detail of the body wall of a cnidarian
Living Shores: Figure 180 B
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
11
PHYLUM CNIDARIA
CLASS
ORDER
HYDROZOA
HYDROIDA
SIPHONOPHORA
Hydroids
Bluebottles
Polyps solitary or bud to form
colonies
12
Floating colonies of several polyplike or jelly-like individuals that
are attached to a stem or disc.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
SCYPHOZOA
ANTHOZOA
Jellyfish or jellies
Sea anemones, zoanthids, sea fans, soft
coral, hard coral
Umbrella shaped jellies
These animals have a barrel shaped body
with a mouth at one end. The mouth is
surrounded by a set of tentacles used for
catching food.
Medusoid stage completely lacking.
CLASS: ANTHOZOA

ANEMONES
Habitat
Some anemones, such as the plum anemones live in small holes and cracks in intertidal zone in
rock pools. Others live in caves and on reefs below the low tide. Sandy anemones crowd into
sandy gullies.
Description
Anemones are simple solitary polyps. They look like
brightly coloured flowers and show a great variety of
sizes and colours. Their bodies’ look like thin sacs
filled with water – like water balloons.
Its mouth is surrounded by tentacles and a curtainlike pharynx that hangs down inside the body and acts
like a valve. This allows food to enter without water
loss.
When exposed to air they withdraw their tentacles,
preventing them from drying out or being damaged.
Feeding
They feed on small animals such as shrimps and fish,
which they catch with the aid of the stinging cells in
their tentacles. Many stinging cells (nematocysts)
contain venomous liquid that subdues the prey. Some
types of stinging cells are barbed and sticky, some
actually wrap around the prey.
Predators
They are eaten by some fish e.g. Butterfly fish and by
some nudibranchs.
Did you know?
Nemo and his dad Marlin – two clownfish- are
exceptions to this, they live symbiotically with the
giant anemone. The clownfish – also known as
anemone fish - shelter amongst the tentacles of the
sea anemone and are protected from the stings by a
special coating of slime.
Clownfish living amongst the
tentacles of a sea anemone
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
13
SOFT CORAL
Habitat
Soft coral is abundant in sub-tidal
zones with a wide depth range off
both the west and East Coast.
Description
They form colonies of polyps with
eight feathery tentacles and are
sometimes brilliantly coloured to
warn of their stinging capabilities. No
solid limestone skeleton.
Feeding
Sunburst soft coral showing the individual polyps
They catch zooplankton (small
microscopic animals) with the stinging
cells in their tentacles.
Predators
Soft corals cannot be very nutritious because much of their bulk is made up of watery mesoglea
(jelly) and their energy content is among the lowest of all animals.
SEA FANS (Gorgonians)
Habitat
Sea fans occur in deeper water growing in caves, on
rocky reefs and in crevices where they are protected
from the force of waves. They are common around
the Cape Peninsula and along the south Coast.
Description
The branched tree-like, colony has a stiff central rod
made up of a flexible material known as gorgonia.
They are usually coloured white, pink, orange or red.
Tiny cup-like polyps are visible on the branches when
they are feeding.
Feeding
The tentacles catch microscopic animals drifting in
the water. They are predators.
Predators
Free-living anemones.
Open polyps
14
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES

HARD CORAL
Habitat
Hard or stony corals grow best in clear, warm waters and their occurrence is limited to the depth
to which light can penetrate the water for the algae that are found associated with the hard coral.
Coral growth is seldom found deeper than 60 metres.
Description
The polyps of corals produce a limestone skeleton, secreted by the outer layer of the body wall. A
few hard corals occur around the Cape for example Noble and Cup coral. Hard corals function as
the main builders of coral reefs. As hard corals lay down more of their underlying limestone or
calcium carbonate skeleton the reef grows. They are also important in providing both food and
shelter to a large number of reef organisms.
Feeding
Colonial corals cannot always obtain enough food from the water and in order to survive they
have great numbers of microscopic algae (zooxanthellae) in their body walls. The algae use
sunlight to make food for themselves and their hosts by means of photosynthesis. Through
digestion, coral polyps release these nutrients to the algae. Coral and algae then apparently cycle
these nutrients between them, reducing nutrient loss to the water.
The coral also protects the algae. This relationship is called mutualism as both these organisms
benefit from this arrangement.
CO2 + H2O  Food (Carbohydrates) + O2 + H2O

Predators
Some species of fish such as parrotfish and butterfly fish, as well as some sea snails and sea slugs,
feed on corals.
Living Shores: Figure 198
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
15


Did you know?
The activity of the zooxanthellae also assists in the release of lime for the
construction of a coral skeleton.
The biggest threat to corals, apart from humans who collect them and pollute the
sea, is coral bleaching.
Coral bleaching
Coral reefs have recently been affected by bleaching i.e. the discoloration or loss of its symbiotic
algae.
The cause of these widespread bleaching incidents is uncertain but recent research indicates that
the cause may be unusually warm waters. The optimum temperature for coral growth is between
26°C and 27°C. Temperatures above 29°C cause the stressed coral polyps to actively expel the
algae giving the coral a bleached appearance.
Bleached corals have difficulty recovering; a reef can take years to recover, and subsequent
bleaching incidents may make it impossible. Without their symbiotic algae, corals are unable to
deposit the calcium carbonate skeleton that makes up the foundation of a coral reef. Not only
corals, but also all reef organisms could potentially lose their habitat because of bleaching
incidents, as the calcium carbonate structure of the reef erodes away.
16
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
JELLYFISH
Habitat
Ocean drifters found
mainly in the open
ocean, but often
wash ashore.
Description
Jellies have rounded
bell-shaped bodies
(medusae),
which
contain a layer of
jelly that consists of
approximately 95%
water. This layer
varies in thickness in
different jellies. They
have tentacles at the
open end of the bell
that is armed with
stinging cells. There is a square mouth with oral arms called
the manubrium.
Feeding
They feed on small fish, shrimps and plankton e.g. fish larvae.
Predators
They have very few predators of their stinging tentacles.
However, they are an important source of food for some
species of turtle and the ocean sunfish.
Plastic bags drifting in the ocean are often mistaken for
jellyfish by these animals resulting in them eating it by
mistake.


Did you know?
Some species are considered a delicacy in Japan.
That the box jellyfish can give a painful sting and
that it’s Australian relative can kill a human being
in 3 minutes.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
17
18
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES

HYDROIDS
Polyps 2mm to hydroid colonies of
25cm
Habitat
Many of the tufts growing on rocks are hydroids and not
seaweeds at all. Some hydroids are found growing on shells of
snails. The hydroids protect the snail by deterring predators
while the hydroids eat the scraps or waste products from the
snail. This relationship is commensalism as the one organism
benefits while the other organism is not harmed.
Description
Hydroids form colonies, which often look like delicate trees or
feathers. Other species of hydroids are branched in an orderly
and elegant fashion. The tiny polyps are borne on the
branches and may be housed in small cups. The polyps can
extend for feeding and can retract into the cups after feeding.
Some hydroids have an external sheath or perisarc made of
chitin and protein. Divers avoid hydroids as they have a fairly
powerful sting.
Microscopic image of hydroid polyps
Feeding
Hydroids are carnivorous and use their tentacles to catch minute shrimps, crabs, fish and eggs
floating in the water. The digestive enzymes of hydroids are able to handle large prey.
Predators
Predators are nudibranchs (sea slugs), flat
worms and butterfly fish.
Did you know?
Hydroids are named after Hydra, the multiheaded goddess of Greek mythology
because they multiply by budding.
The Goddess grew two heads in place of
every one Hercules cut off.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
19
BLUEBOTTLES
Habitat
Bluebottles live on the surface of the open ocean, but are often blown ashore by onshore winds.
Description
They are unusual hydroid colonies, which consist of
highly specialised individuals that are all
interdependent.
Feeding
They prey on small fishes that they catch with their
tentacles.
Predators
Marine turtles and sea swallows prey on bluebottles.
Plough snails and sea slugs (nudibranchs) may eat
bluebottles washed ashore.
Structure of the bluebottle or
Portuguese man-o’-war
Living Shores: Figure 186
The smaller raft hydroid with a circular raft and
the by-the-wind sailor with an oval raft and
vertical sail are smaller colonies similar to the
bluebottle. They set sail to the wind as a colony,
producing a thin bright blue membrane of stiff
material, orientated diagonally across the colony’s
body.
20
Did you know?
The painful stings of a bluebottle
should be washed off with salt
water and are best treated with sap
from the leaf of a sour fig plant or
vinegar. A medical practitioner
using antihistamines should treat
severe cases.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
Quick review
1.
Identify the animals shown in the table below by giving the Phylum and the common
name.
Phylum:
Phylum:
________________________
Common name:
______________________
Common name:
2.
List three characteristics that all Cnidarians have in common.
3. Label the following parts on the animal below.
b
a
4. Name one interesting thing you would share with a visitor at the touch pool
________________________________________________________________________________
________________________________________________________________________________
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
21
PHYLUM: PLATHYHELMINTHES
FLATWORMS
CHARACTERISTICS

Free living (living independently i.e. not attached)

Bilaterally symmetrical with a definite front and back, and with left and right sides.

Mobile creeping animals.

Concentration of sensory organs at the front of body = eye spots
Habitat
Flatworms can be found gliding over rocks in rock pools. One species lives under the foot of the
ocular limpet. Parasitic species include flukes and tapeworms. Flatworms generally remain hidden
under rocks.
Description
Free-living marine forms are very flat leaf-like worms. They range in size from almost microscopic
to 60 cm in length. Some are drab and others are very colourful. Flat worms are often mistaken
for sea slugs.
Feeding
They prey on anything that is small enough or slow enough for them to catch e.g. small molluscs,
crustaceans. Some flat worms eat sponges and hydroids. They are able to swallow the stinging
cells of the hydroids without triggering the sting capsule. They may also scavenge on dead
animals.
Predators
Fishes are the main predators of flatworms.
22
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
Did you know?




Flat worms store food reserves in their cells and can go without food for long
periods.
When starved they begin to digest their own tissues, starting with their
reproductive organs.
The animal can shrink to a hundredth of its original size and still remain alive.
When food is once again available, the worm grows bigger and regenerates the
missing organs.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
23
PHYLUM: SIPUNCULIDA
PEANUT WORMS
CHARACTERISTICS

Soft bodied.

Worm-like.

Unsegmented.

They have an enormously extensible front part of the body (the introvert), which can
be shot out or rolled back into the body with equal ability.
Habitat
Sandy areas between rocks and shells. The majority are bottom-dwellers in shallow water.
Description
Peanut worms tend to have a dull appearance. They are light brown worms, which look
remarkably like a peanut. The body consists of two main parts:
- a cylindrical, bottle-shaped or sac-like structure, the trunk;
- a more slender extendable introvert which can be completely withdrawn into the trunk.
Feeding
They feed on detritus (dead organic matter) that settles out under the rocks, algae and diatoms.
The tentacles are used for gathering
food.
Predators
Fishes eat peanut worms.
A
B
Figure: (A) withdrawn and (B) extended view of a peanut worm.
Did you know?


24
The introvert is used for both feeding and locomotion.
The introvert can be extended up to four times the length of the worm’s body.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
LONG, LONG AGO . . . . . .
Six hundred million years ago, three kinds of animals appeared in the seas:

Segmented creatures;

Shelled animals;

And others with five rays.
They established four great groups of today’s animals:

Segmented Annelida and Arthropoda;

Shelled Mollusca;

And five rayed Echinodermata.
PHYLUM: ANNELIDA
Annule = ring shaped markings- segmented
CHARACTERISTICS

Segmented worms.

Bilaterally symmetrical.

There is a distinct head formation (cephalization).

The heads have a variety of frills, jaws and feelers.
CLASS: POLYCHAETA
(poly = many; + chaetae = stiff hairs)
This class includes the bulk of the marine worms and are characterised by having many bristle-like
stiff hairs called chaetae.
Two types of worms are described here - the active and free-living worms (e.g. the mussel worm)
and the sedentary or tube dwelling worms (e.g. reef worms).
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
25
PHYLUM: ANNELIDA
CLASS: POLYCHAETA
CHARACTERISTICS

Active.

Uniformly segmented bodies.

A pair of large paddle-shaped appendages (parapodia)on each segment with long
bristles (called chaetae)

Internal jaws.

Well-developed sensory organs on head.

1. FREE-LIVING WORMS
Habitat and description (structure)
Mussel worm
Lives on rocks among
mussels and seaweeds in
the intertidal zone.
Used as bait species but its
collection destroys large
areas of mussel beds.
Wonder worm
Common under boulders,
especially where gravel
allows them to burrow.
Large jaws inflict a painful
bite
Used as a bait species.
Scale worm
Common in rocky-shore
pools, rock crevices and
beneath boulders from low
shore to the shallow sub
tidal.
Feeding
Shoot out their jaws to catch small animals such as shrimps and other small worms.
Predators
They are eaten by fish and crabs or even by other species of polychaetes.
26
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES

2. SEDENTARY WORMS
CHARACTERISTICS

Normally inactive, tube dwelling, with small parapodia.

Head often modified with elaborate appendages that extend into the water for filter
feeding.

Lack (no) jaws.
Habitat and description (structure)
Tangle worm
Lives in a mucous tube, which is
decorated with sand or pieces of
shell.
Grooved tentacles extend to
capture food particles that settle
on them. They feed on detritus detritivores
Spiral fan worm
Abundant everywhere,
dotting most rocks in the
shallow subtidal pools, on
shells or sea plants.
Filterfeeders
Reef worms
Form extensive reefs on
rocks at the mid-tide region,
especially along the Atlantic
coast.
Cements sand grains to its
tubes.
Filterfeeders
Feeding
Most of them are filter feeders. Others spread their long feeding tentacles over the sand or rock
in a sticky web to catch small animals.
Predators
Whelks and butterfly fish eat these sedentary worms.
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES
27
Quick Review
1.Provide the Phylum and common name of the animals illustrated in the table below.
Phylum:
__________________________
Common name:
Phylum:
Phylum:
__________________________
Common name:
Phylum:
__________________________
Common name:
__________________________
Common name:
2. List TWO interesting facts for each of the following three worms.
2.1 Flatworm
a.
b.
2.2 Wonder worm
a.
b.
2.3 Spiral fan worm
a.
b.
28
Two Oceans Aquarium Volunteer Manual – Module 4 – INVERTEBRATES