4 invertebrates

BY1102 Introduction to Evolution, Biodiversity and the Environment

Feeding strategies &

Species diversity

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1. There are 4 main feeding types of animals. Which are they and give examples.

1. Suspension/filter feeders: feed on particles suspended in the surrounding water

2. Fluid feeders: feed on fluids (e.g. blood, nectar) of another organisms

3. Substrate feeders: feed on what they live in (soil)

4. Bulk feeders: eat pieces of other organisms or swallow them whole


2. What does each phylum eat? – Name the animal phylum


2. What does each phylum eat? – Main characteristics Lack symmetry Lack true tissues

Radial symmetry Diploblastic (2 germ layers)

•Bilateral symmetry •Triploblastic •Coelom (body cavity)

Protostome development (mouth from blastopore)

Embryonic development (anus from blasopore)


2.1 Give an example of an animal for each phylum 2.2 What does each phylum eat?


2. What does each phylum eat? Give an example of an animal for each phylum

Porifera: Glass or calcareous sponges or demosponges

Filter-feeding Small particles in water e.g. small crustaceans bacteria

Ctenophora: e.g. Sea gooseberries & comb jellies

Bulk feeders Zooplankton

e.g. fish eggs, copepods, amphipods, larvae


Cnidaria: e.g. anemones, jellyfish and corals

Bulk feeders Zooplankton

e.g. small crustacean

Equinodermata: e.g. starfish, sea urchins, sea cucumbers

Filter-feeding or Substrate feeders

e.g. small particles in water or grazers


Chordata: e.g. humans and other mammals, birds, fish, frogs, sea squirts...

All types of feeders

Platyhelminthes : a.k.a. flatworms; e.g. Taenia, planarian, flukes and tapeworms


e.g. carnivorous / parasites (eg. tissues, small investebrates)


Brachiopoda: a.ka. lamp shells

Mollusca: e.g. Octopus, clams, snails

All types

e.g. Herbivores, carnivores, filter feeders

Filter-feeding

e.g. fine particles in water


Annelida: e.g. ringworms: earthworm, leech, lugworm...

Nematoda: Roundworms e.g. C. elegans

All feeding types

e.g. Decomposers: bacteria and detritus / carnivores: small crustaceans/or parasites

Fluid & substrate feeders

e.g. Blood or decomposers (undecayed leaf and other plant matter)


Arthropoda: e.g. Insects (eg. mosquitos), spiders, crustaceans (lobsters)


e.g. Blood, carnivores, herbivores...


3. Describe the adaptations of herbivores and plants

Plant Herbivores

1. Chemical defences • chemical compounds that are toxic and repel or reduce digestibility (e.g. nicotine and cocaine)

2. Physical defences

• thorns, spines 3. Bodyguards

• induced or constitutive

1. Chemical defences • enzymes that counteract toxins or sensors (less toxins and higher quality nutrients)

2. Physical defences

• specialized mouthparts, teeth, hard tongues, fewer soft body parts

3. Metabolic/behavioural adaptations

• seasonality, symbioses with e.g. bacteria to help digestion, low metabolic rates


4. Describe the adaptations of predators and prey

Prey Predator

1. Camouflage • Species resembles its background.

2. Senses

• Sight, hearing, smell

3. Warning signals • Noises, visual/smell signals (e.g. shunk)

4. Defensive ‘weapons’

• Chemical defenses, weapons (claws/teeth)

5. Behavioural adaptations

• Living in groups, hiding, mimicry

1. Senses • Species resembles its background.

2. Hunting strategies

• Stalk, sit&wait, group hunting, lures

3. Physical adaptations • Strength, jaws/claws, stamina, tongues

4. Behavioural adaptations

• Speed, communication


5. Describe the evolutionary consequences of predator-prey coevolution

Describe coevolution.

Predation influences the fitness of both predators and prey. Individuals must both feed and avoid being eaten to survive and reproduce. Genetically-determined traits that improve an organism’s ability to survive and reproduce will be passed on to its offspring. Traits associated with improved predation for predators and escaping predation for prey tend to be positively selected by natural selection.

- two (or more)species reciprocally affect each other’s evolution.


Read: “The Maintenance of Species Diversity”

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4 invertebrates