Two Oceans Aquarium Volunteer Manual – Module 3 – INVERTEBRATES 1

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 41

Phylum Mollusca 42

Phylum Echinodermata 58

Phylum Chordata 65

Two Oceans Microscope 67

Key Concepts Underline or highlight the concepts as you read through the notes.

1. Why is classification important? 2. Name of Phylum and main characteristics. 3. Methods of feeding 4. Different kinds of symmetry and the advantages of each. 5. 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

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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 are known as taxonomy.

CREATING ORDER OF THE LIVING WORLD

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.

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ANIMAL KINGDOM NON-LIVING WORLD

Phylum

Class

Order

Family

Genus

Specie

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

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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

Soft Corals and Sea Fans

Jellies

Hydroids

Bluebottles

PHYLUM: PLATYHELMINTHES

Flat worms

Bilateral symmetry

Not segmented

Eye spots

PHYLUM: SIPUNCULIDA

Bilateral symmetry

Not segmented

Introvert and trunk

Flatworms

Peanut worm

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PHYLUM: ANNELIDA

Ring – like external bands - segmented

Bilateral symmetry

Bristle worms

Jaws or modified mouth parts

Sedentary (live in tubes) worms

Free living 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

Hermit crabs True crabs

Isopods and Amphipods

Barnacles

Shrimps, Lobsters, Prawns

PHYLUM: MOLLUSCA

Soft body

Bilateral symmetry

Most examples have a shell

Limpets

Bivalves

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Sea snails

Chitons

Sea slugs or Nudibranchs

Octopus Squid

PHYLUM: BRYOZOA

Look like seaweeds, corals or hydroids

Build colonies

PHYLUM: CHORDATA

Bilateral symmetry

Include all Vertebrate classes

All have similar features in larval stage = tadpole like

Dorsal Nerve chord

Stiff dorsal rod (notochord)

Pharyngeal gill slits

Moss or lace animals

Sea squirts Individual or colonial Cellulose casing = tunic

PHYLUM: ECHINODERMATA

Spiny skin

Pentaradial (5 part ) symmetry

Endoskeleton ( on the inside)

Tubefeet

Starfish

Sea urchin

Brittle star

Sea cucumber

Feather star

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Fig 11. Showing radial symmetry of sea anemone

Central point

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)

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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 which eats other animals

Radial symmetry Animals with a circular body plan

Herbivore Animals without a backbone

2.

In the table below number the names given from highest classification to lowest classification.

Genus Phylum Class Family Order Species

3. Why is classification so important in the naming of animals? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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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

PHYLUM: PORIFERA (pori = pores and fera = bearer)

SPONGES

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 animal-like 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.

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.

Living Shores: Figure 175

Flagella beat to create water movement for feeding

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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.