A variety of sea life and freshwater animals observed using microscopes
Useful information
Kit List: 

Volvox, rotifers, daphnia, paramecium, algae, hydra (ordered from the schools supplier Blades Biological)
Microscope (ideally with a link to a tv) - for CBS we have historically borrowed the video microscope from the zoology lab
Petri dishes
Pasteur Pipettes


Look at miniature sea life and freshwater animals under a microscope. Key message is that there are organisms that are smaller than we can see just with our eye.

Possible Activities:
1) Look at different animals under the microscope – discuss their characteristics
2) Discuss microscopes and the concept of scale/size (i.e. with hairs under the microscope, etc)

Focus less on the biology and more on scale for much smaller children. Focus on the idea that every puddle is full of little animals so small they can't see them. Be sure to use simple language!


1) Fill a small petri dish with water from a sample jar and introduce a hair for scale. Ideally a fair hair, as the sample is illuminated from below.
2) Then start looking at the rotifers.
3)Talking points:
a. Do they know what a microscope is? It can help to compare it to a telescope (telescopes let you see things far away, microscopes help you see very small things that are close by). Make it clear that what they are seeing through the microscope is the stuff in the dish of water.

b. You can get them to look at a hair through the microscope and try and guess what it is (a fair hair works better). You can often see the scale-like texture and so can talk about how things can appear quite different when you look at them close up.

c. Find a rotifer - talk about how small they actually are (compare them to the hair), identify anatomical parts.
Talk about the corona which are two wheels covered in little hairs on his head. When these spin, it makes the water spin which shoots any food in the water straight into its mouth.
You can often see its jaws moving, which they might think is its heart beating but rotifers don't have hearts, or brains, or eyes.
Talk about where they live - gutters, bird baths, puddles (anywhere wet that occasionally dries out). When it dries out, they dry out too and stop moving etc. - this is called anhydrobiosis. They replace the water in their body with sugar and can live for years like this. Within 5 minutes of being in water, they 'come back to life'.

d. Rotifers are about 50-60 cells but paramecia are single cells (a big difference in size). The paramecia are covered in cillia which beat like a mexican wave to power them through the water and have a trench in their body in which they hold their food (bacteria, algae and yeasts).

e. Amoeba are also single cells, but they move by extending their membrane in some places (a ‘pseudopod’) and retracting it in others, unlike paramecia which use cilia. Often find them in decaying vegetation in fresh and salt water. They eat by endocytosis – they engulf food in their membrane.

f. Volvox – these are made of numerous cells each with 2 flagellae all interconnected and arranged in a sphere (filled with glycoproteins) – all the cells swim together in a coordinated way. Can see daughter colonies developing inside. Found in ponds, ditches and shallow puddles.

g. Daphnia – ‘water fleas’ (0.2-0.5 mm long). 5 or 6 pairs of legs. Can see heart beating (~180 bpm). Mainly eat single-celled algae.

h. Hydra. Freshwater animals. A few mm long. Tubular body, anchored at one end and with mouth and surrounding tentacles at other end. Some live in mutual relationship with algae – the algae photosynthesize to produce food for the hydra, and the hydra give the algae protection from predators. Can produce young by budding.

i. Algae. Simple plant-like creatures. Some unicellular, others multicellular. Can photosynthesize. Bottom of lots of food chains.

Risk Assessment
Date risk assesment last checked: 
Tue, 07/01/2020
Risk assesment checked by: 
Polly Hooton
Date risk assesment double checked: 
Sat, 25/01/2020
Risk assesment double-checked by: 
Risk Assessment: 

Use microscope to look at miniature sea life and freshwater animals on a TV screen.

Hazard Risk Affected Person(s) Likelihood Severity Overall Mitigation Likelihood Severity Overall
Organisms/Protozoa Could cause harm if ingested or enters via wounds. All 2 3 6 Do not let children eat organisms. Remind them to wash hands afterwards if they have touched apparatus. Recommend that cuts are covered. Only let older children move the petri dish. Keep stocks away from children. We only use protozoa from standard school suppliers.
If ingestion occurs, advise family to see GP if signs of sickness are shown and provide notes of what was ingested.
1 3 3
Glassware Cuts from broken glass. All 3 3 9 Keep children under control. Dispose safely of any broken glassware immediately (sharps bin).
In case of accident, call first aider.
2 2 4
Plastic pipettes Poking risk especially to eyes. Children 3 3 9 Supervised use of pipettes only. Do not let very young children use them. Keep away from eyes. Take off of children if they are messing about.
In case of accident, call first aider.
1 3 3
TV Microscope is a heavy object which could cause injury if falls, electrical risk (especially in connection with water and sea water) - sea water contains more ions and conducts electricity better than fresh water. All 2 3 6 Place TV away from the edges of table, preferably against a wall so that it cannot be knocked off easily. Ensure electrical equipment has been PAT tested within the last 2 years. Keep equipment dry by keeping hands dry. Do not put TV near water, especially sea water. See separate electrical parts risk assessment.
Switch off power at mains if a problem arises with the TV. Clear the area of people and call first aider if anyone is injured. In case of electrocution, do not go near casualty. Try to isolate the power without danger to yourself, and call ambulance.
1 3 3
Lamps Hot objects which could cause burns, electrical risk (especially in connection with water and sea water). All 3 3 9 Only switch lamps on when necessary. Do not touch and warn visitors not to touch them either. Ensure electrical equipment has been PAT tested within the last 2 years. Keep equipment dry by keeping hands dry. Do not put lamps near water, especially sea water. See separate electrical parts risk assessment.
If person gets a burn, run cold water over affected area for at least 10 minutes, and call a first aider. Switch off power at mains if you suspect an electrical problem. Call first aider if there is a casualty.
2 2 4
Sea water collection Risk from tide. Demonstrators 2 3 6 Demonstrators only to collect sea water, and only if it is safe to do so (eg. don't go in a place where the tide is about to trap you). Cover cuts. Wash hands well afterwards. Ensure that if the volunteer gets wet they warm up properly.
Contact GP should illness develop. Call a first aider in case of injury.
1 3 3
This experiment contains mains electrical parts, see separate risk assessment.
Publicity photo: