Life cycles

Introduction
Public summary: 

Ever wondered what happened to a creature between it being an egg and an adult? Look at our life cycles collection for Bees and Frogs and see for yourself!

Perpex blocks with specimens of frogs and bees from different lifecycle stages
Useful information
Kit List: 

Sets of preserved life cycles of frogs and bees.

Honeybee - egg, larvae, and pupa; worker bee, drone, and queen bee; pollen, honey, and royal jelly; foundation honeycomb, drone cells, and queen cell; worker bees collecting nectar

Frog - eggs, tadpole, various stages from tadpole to frog, adult, magnifying glass

Beeswax candle set

Packing Away: 

Pack blocks into the right boxes carefully.

Frequency of use: 
5
Explanation
Explanation: 

*** OVERVIEW/THINGS YOU MIGHT LIKE TO TALK ABOUT ***

- The life cycles of frogs and bees. Can use butterfly life cycles as an introduction for younger kids as they should definitely know this.
- Social structure of bee colonies and communication amongst bees
- Using stages of insect development to "date" a decomposing corpse

*** BASIC PROCEDURE AND EXPLANATION ***

1) Let them pick which life cycle they want to look at first. Ask if they know what animal it is.

2) Tell them the blocks show the lifecyle of the animal. Explain the concept of lifecycles i.e. that animals change throughout their lives and then the adult can reproduce to start the cycle again.

3) Ask the child to put the blocks in the correct order. Talk them through it when they're done. The blocks were numbered so stickers have been put over these to stop the kids using this. The frog order goes red, yellow, blue, orange, blue, yellow, green. The bee box should have a sheet explaining what is in each block.

4) Start by describing the egg. This is one cell (a tiny ball of nutrient and information (DNA)) which divides lots and lots of times to produce larvae.

5) Next discuss the larvae/tadpole. Emphasize how the larvae spends all its time eating and eating and eating so it can grow really fast and store energy for metamorphosis!

7) Explain the pupae stage for the bee - at this point the larvae undergoes metamorphosis and becomes an adult! What is metamorphosis? It refers to something changing from one form to another completely new form. Isn't it amazing that the larval form can change into the adult form in just about two weeks?!

8) After you've finished explaining the life cycle of the animal, you might ask the child if humans go through metamorphosis. Explain that while humans don't go through metamorphosis, we do change a lot in our mummy's tummy! We also go from an egg (one tiny cell smaller than the full stop at the end of this sentence) which divides lots of times to create a baby!

*** EXTRA INFO ***

**BEES**
Larvae -> Pupae -> Worker/Queen
1) Social Structure of Bees (http://www.indianchild.com/honey_bee.htm)
- Each bee colony has a very organized social structure.
- Bees tell each other where food is through different dances - call these waggle dances
Males/drones:
- Develop from unfertilized eggs (parthenogenesis) - means females can produce as many males as they want to (as don't have to mate with male first)
- mate with queen to produce new queen
Worker bees;
- Develops from fertilized eggs
- jobs like clean/ incubate eggs/feed drones and larvae/guard hive/find food
Female bee: Queen
- Develops from fertilized eggs
- lays eggs, mother to all bees in the colony. ~2000 eggs/day
- Produces pheromones which controls the behavior of her workers
- Fed lots food! Fed royal jelly from larvae rather than normal honey which has epigenetic factors which cause it to develop into a Queen rather than a worker.

2) Communication Among Bees (http://www.indianchild.com/honey_bee.htm)
- Bees communicate by pheromones (chemicals produced by the queen that the other bees "smell") and dances.
- This communication is very important to maintain the organization/social structure within the colony so that all of the bees can survive (the queen, workers, and drones cannot live alone - they depend on each member of the colony).
- Dancing - round dance, go in a circle and waggle in the direction of food is in (long distance). Waggle dance, food is nearby direction of run indicates direction and length of waggle shows how far.
- Stingers, die after they've stung as pulls organs with it. (different in wasps)

Honey. Why do they make it? What from? Uses nectar to feed larvae. Honeycomb, useful to farmers as pollinators.

**FROGS**
1) Egg -> Frogspawn -> Tadpoles -> Frogs

2) Frogspawn is like jelly, provides a food source for the growing embryo (the black spot)

3) Tadpoles - sometimes eat each other (cannibalism). They start with no legs, then develop hind legs, then front. Then become froglets.

4) Tree frogs; where do they lay their eggs? - in the water collected at the bases of leaves. Are often brightly coloured and very poisonous (used to make poison arrows. The Golden Tree Frog is toxic enough to kill 20 people or two elephants, chickens and dogs have died from touching paper that has been touched by a frog! Poison stops nerve impulses leading to muscle contraction.

Amphibian, need to stay damp as they breathe through their skin, like lungs aveloli. They're vertebrates and have a backbone.

**BUTTERFLIES**
Ova -> Larvae -> Pupae -> Adult
1) Patterns/colouration - eye spots deflect attack from the butterfly's body , camouflage is another way of increasing the likelihood of survival allowing it to rest undetected

3) Forensic Entomology: (http://www.forensicentomology.com/appear.htm)
- Forensic Entomology examines the stages of develop of insects in a decaying corpse to determine when the body died!
- For example, many insects will lay eggs on a corpse. These eggs will hatch and become larvae, which feed on the decaying corpse. By examining the size/weight of the larvae, these scientists can determine how old the corpse is!

caterpillars eat vegetables, 14 years of eating before they turn into a butterfly, they can be poisonus and brightly coloured to warn predators. Some butterflies only live a couple of weeks. Have bright colours to warn birds they taste bad and eye spots and camouflage. Monarch butterflies migrate from Canada to Mexico (3000 miles) using landscape (mountains/sun) to navigate. Some moths use earth's magnetic field. Some eat plants like milkweed which make them poisonous to other animals.

*** SCIENCE BACKGROUND FOR DEMONSTRATORS ***

More information on Forensic Entomology (http://www.forensicentomology.com/appear.htm)
"What information can a forensic entomologist provide at the death scene?"

Forensic entomologists are most commonly called upon to determine the postmortem interval or "time since death" in homicide investigations. The forensic entomologist can use a number of different techniques including species succession, larval weight, larval length, and a more technical method known as the accumulated degree hour technique which can be very precise if the necessary data is available. A qualified forensic entomologist can also make inferences as to possible postmortem movement of a corpse. Some flies prefer specific habitats such as a distinct preference for laying their eggs in an outdoor or indoor environment. Flies can also exhibit preferences for carcasses in shade or sunlit conditions of the outdoor environment. Therefore, a corpse that is recovered indoors with the eggs or larvae of flies that typically inhabit sunny outdoor locations would indicate that someone returned to the scene of the crime to move and attempt to conceal the body.

Similarly, freezing or wrapping of the body may be indicated by an altered species succession of insects on the body. Anything that may have prevented the insects from laying eggs in their normal time frame will alter both the sequence of species and their typical colonization time. This alteration of the normal insect succession and fauna should be noticeable to the forensic entomologists if they are familiar with what would normally be recovered from a body in a particular environmental habitat or geographical location. The complete absence of insects would suggest clues as to the sequence of postmortem events as the body was probably either frozen, sealed in a tightly closed container, or buried very deeply.

Entomological evidence can also help determine the circumstances of abuse and rape. Victims that are incapacitated (bound, drugged, or otherwise helpless) often have associated fecal and urine soaked clothes or bed dressings. Such material will attract certain species of flies that otherwise would not be recovered. Their presence can yield many clues to both antemortem and postmortem circumstances of the crime. Currently, it is now possible to use DNA technology not only to help determine insect species, but to recover and identify the blood meals taken by blood feeding insects. The DNA of human blood can be recovered from the digestive tract of an insect that has fed on an individual. The presence of their DNA within the insect can place suspects at a known location within a definable period of time and recovery of the victims' blood can also create a link between perpetrator and suspect.

The insects recovered from decomposing human remains can be a valuable tool for toxicological analysis. The voracious appetite of the insects on corpses can quickly strip the remains down to the bones. In a short period of time the fluids (blood and urine) and soft tissues needed for toxicological analysis disappear. However, it is possible to recover the insect larvae and run standard toxicological analyses on them as you would human tissue. Toxicological analysis can be successful on insect larvae because their tissues assimilate drugs and toxins that accumulated in human tissue prior to death."

Risk Assessment
Date risk assesment last checked: 
Sun, 13/01/2019
Risk assesment checked by: 
Polly Hooton
Date risk assesment double checked: 
Sun, 13/01/2019
Risk assesment double-checked by: 
Grace Exley
Risk Assessment: 

Looking at dead insects in perspex blocks & talking about them.

Hazard Risk Likelihood Severity Overall Mitigation Likelihood Severity Overall
Perspex blocks Kids may throw them or drop them on feet 2 1 1 Take away from kids if they are being silly with them. 1 1 1
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