UNIT 5.- INVERTEBRATES 1ST ESO
INVERTEBRATES LEARNING CENTRES ACTIVITY
INTRODUCTION
An invertebrate is any animal without a backbone. Invertebrates make up 95% of all species of animals on the earth, and the variety of invertebrates is enormous. Scientists group or “classify” all of these different types of animals into broad categories called phyla, on the basis of their patterns of symmetry and on the basis of their overall body plan. There are 5 particularly important invertebrate phyla (and another 23 or so less important phyla). The major invertebrate groups are classified as:
· Phylum Porifera
· Phylum Cnidaria: sea anemones, corals, and jellyfish
· Phylum Platyhelminthes
· Phylum Annelida: segmented worms
· Phylum Mollusca: clams, snails, and squids
· Phylum Arthropoda: lobsters, beetles, crabs, and flies and scorpions
· Phylum Echinodermata: sea urchins, sea cucumbers, and starfish
In this activity you will be working with different sheets and microscopes in order to learn to identify the main types of invertebrates of the Animal Kingdom.
MATERIALS
· Seven stations around the lab or classroom.
· As many microscopes and samples of these animals as the school can provide.
· The rest of them can be supplied by different pictures.
· Flashcards with the main features of each phylum, placed in each station.
· These sheets are provided as annexes of this document.
PROCEDURE
1. Distribute the class in groups of four students. Your teacher will assign your group a particular learning centre to start off. You will have five minutes before you are sent to the next station.
2. Once you are placed there, observe the picture of the animal and read carefully the card attached to it.
3. Read the questions asked and discuss them with your partners.
4. Answer them accurately and move to the next station when you are required.
5. At the end of the lab your team needs to cover all the centres and answer all the questions and make a drawing of the animal.
QUESTIONS
In order to solve some of these questions you should use some bibliographic sources. Cite them at the end of your report under the head of “references”
Make a drawing of each one of them
§ Phylum Porifera
1. Do you think this organism can move?
2. What do you think it eats?
3. Is it a plant or an animal? Why?
§ Phylum Cnidaria: sea anemones, corals, and jellyfish
1. How is the symmetry of this animal?
2. What would be the purpose of having stinging cells?
3. Do they have a brain?
§ Phylum Annelida: segmented worms
1. Which end is the head end?
2. Is the body segmented? How many segments can you count?
3. How would you describe its digestive system?
§ Phylum Mollusca: clams, snails, and squids
1. Does this organism have a skeleton?
2. How many tentacles does it have?
3. Name an organism it might be related to
§ Phylum Arthropoda: crustaceans, arachnids and insects
1. What do you think the grooves on its back are used for?
2. How many body sections can you count? How many legs?
3. How many mouthparts can you count?
§ Phylum Echinodermata: sea urchins, sea cucumbers, and starfish
1. How do you think this organism eats?
2. Does it have a brain?
3. Where does it live?
4. What kind of symmetry does it have?
CORRECTION
1. Do you think this organism can move?
No it cannot, it is sessile
2. What do you think it eats?
Anything that is soluble in water or can be filtrated by the pores and can cross the cell membrane of the cells
3. Is it a plant or an animal?
It is the simplest animal. It has not a plant cell
1. How is the symmetry of this animal?
It hasn’t a particular one, although it tends to be radial
2. What would be the purpose of having stinging cells?
Defend themselves from potential enemies
3. Do they have a brain?
No, they haven’t. But it includes a network of nerve cells.
1. Which end is the head end?
The one closest to the mouth.
2. Is the body segmented? How many segments can you count?
Yes it is. Innumerable. Leeches are the onlyannelidswith a fixednumber(34) of bodysegments
3. How would you describe its digestive system?
It consists generally of a straight tube; a mouth leads into an oesophagus, which is followed by the intestine and the anus
1. Does this organism have a skeleton?
It has no internal or externalskeletonwhich means that theoctopusis able to squeeze itself into tight places.
2. How many tentacles does it have?
Eight
3. Name an organism it might be related to:
Squid
1. What do you think the grooves on its back are used for?
The ladybugs and beetles in general, carefully avoid soiling their food material and store their frass (the faeces) in the areas between the grooves. They lay their eggs along the frass ridges, and the larvæ which hatch out feed upon the same nutritive parenchyma as their parents
2. How many body sections can you count? How many legs?
Three sections head, thorax and abdomen and three pairs of legs.
3. How many mouthparts can you count?
Ladybugs, both adults and grubs, use their chewing mouthparts to eat other insects, fruit, nectar, leaves, fungi, dead animal and plant material, and/or wood
1. How do you think this organism eats?
It’s got a mouth touching the seabed. The mouth is in the centre on the underside. They prey on bivalves like mussels and clams, as well as small fish, snails, and barnacles
2. Does it have a brain?
A sea star has no head. It has no brain either. But a sea star doesn’t need a brain to sense what is going on around it
3. Where does it live?
The Starfish, or Sea Star, is a bottom-dwelling marine animal.
4. What kind of symmetry does it have?
Pentameral, which means that it has five symmetrical parts.