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3. Eggs are common among: Vertebrates including fish, reptiles, amphibians, birds and mammals and Invertebrates including insects and crustaceans, arachnids, (spiders and ticks), molluscs (like squid and clams). Click screen to continue

4. There are about 9000 kinds of birds in the world, and all baby birds hatch out of eggs. Birds’ eggs are hard shelled. A single young hatches from each egg. The mother bird lays the eggs and they must be kept warm. Bird eggs are incubated for a time that varies according to the species. The average clutch sizes range from one (as in condors) to about 17 (some partridge). Some birds lay eggs even when not fertilized. Sometimes pet owners find their lone bird nesting on a clutch of infertile eggs. Most bird eggs have an oval shape, with one end rounded and the other more pointy. This shape results from the egg being forced through the oviduct.

5. Although all the eggs of different birds look different on the outside, they are very similar inside. Each egg contains all the basic things that a baby bird needs to grow. The egg protects and nourishes the young embryo. The white part of the egg (albumen) provides a protective cushion and contains water for the embryo. The yellow part (yolk) is a food store, providing the growing embryo with the nourishment it needs to develop. The shell offers further protection. The underlying membranes provide a barrier to bacteria that might otherwise penetrate the egg. Each egg is a self-contained life-support unit for the developing young bird. Bird eggs, which are laid out of water, are surrounded by a protective shell. Tiny pores in bird eggshells allow the embryo to breathe (a hen's egg has around 7500 pores).

6. Why do different kinds of birds lay different coloured eggs? The answer has a lot to do with where the eggs are laid. If the eggs are in a nest of leaves and twigs, speckled green and brown eggs will be difficult for egg-eating predators to find. On a rocky ledge, grey and black spots will help to hide the egg. Birds that have white eggs usually lay them out of sight, inside tree hollows or in burrows, so there is no need to camouflage them. In places where many birds are nesting near each other, such as rocky sea cliffs, different markings may help the parents recognize their own nests.

7. Sizes That Surprise Us The largest egg comes from the ostrich - 1.5 kilos - 180 mm long & 140 mm wide. Hummingbirds lay the smallest eggs of any birds- the size of a jelly bean! (about half a gram -13 mm long and 8 mm wide) The ostrich egg is over 2000 times larger than the smallest egg produced by a hummingbird. A kiwi is only 4 times bigger than her egg. Bird eggshells vary widely, e.g. Cormorant eggs are rough and chalky Duck eggs are oily and waterproof Cassowary eggs are heavily pitted

8. tortoise snakes lizard The first animals to live full-time on the land were reptiles (descendants of dinosaurs). Reptiles are cold-blooded vertebrates and include snakes, lizards, crocodiles, turtles and tortoises, typically having a dry scaly skin and laying soft-shelled eggs on land. turtle

9. The parts of the hard-shelled egg of a reptile protect and nourish the young embryo. Hard-shelled eggs are laid out of water and must contain the water necessary for life and growth. snake laying eggs The white part of the egg, called the albumen, provides a protective cushion and contains water for the embryo. The yellow part, or yolk, is a food store, providing the growing embryo with the nourishment it needs to develop. The underlying membranes in the shell provide a barrier to bacteria that might otherwise penetrate the egg and the shell offers further protection by keeping moisture and warmth in and predators out. Reptiles add layers of leathery proteins around their eggs to protect them physically, and help the eggs retain their internal moisture in an environment out of water. Each egg is a self-contained life-support unit for the developing reptile.

10. Snakes can be born in different ways. Not all reptiles lay eggs, but most kinds of snakes (about 70%) lay leathery eggs which will hatch in several weeks. Snakes that lay eggs are called oviparous. Most oviparous snakes do not provide any care for the eggs or the hatchlings. They don’t build nests but simply lay the eggs in holes or hollows or even on the bare ground in damp, warm places. Some snakes, including sea snakes, adders, and some garter snakes, do not lay eggs. Instead, the eggs develop inside the mother’s body and hatch while still inside her. She then gives birth to a batch of live snake babies. Snakes that use this method are called ovoviviparous. Some are viviparous – live young which have developed inside the parent.

11. Turtles are on their own right from the start. The mother turtle buries her roundish eggs in the ground and leaves them to hatch by themselves. They must dig out of their nests and set out on their own, watching out for predators who like to eat the babies before their shells harden. Crocodilians bury their eggs under soil and leaves and guard this nest against predators for eleven to fourteen weeks. The mother digs the eggs up when they are ready to hatch and watches as her babies break out of their shells. They use an ‘egg tooth’ on the tip of their snout for this, but the mother is there to help them if they get stuck. For the first few months of their lives, she will lead them to water and protect them from harm.

12. Indian pythons wrap their bodies around the eggs and shiver to keep the eggs warm. Reptile eggs are often rubbery and are always initially white. Often the sex of the developing embryo is determined by the temperature of the surroundings, with cooler temperatures favouring males.

13. ladybirdgrasshopper beetle List all the insects you can that lay eggs and see if you can find out where they lay their eggs. Some butterfly and moths lay eggs on the underside of leaves. To do: Collect some insect larva and predict how big it will grow and what will happen to the larva when they are finished growing. Record measurements and observations daily and add diagrams. Preying mantis and egg case caterpillarbutterfly

14. Fish lay eggs in the water. They have special ways to keep them safe. The soft-shelled eggs laid by fish must be laid in water or they would dry out. Fish eggs are jellylike and are fertilized externally. Fish eggs are squishy, and water can pass through them to bring oxygen to the developing young. These eggs are often covered in a gooey jelly that protects them from diseases. Some fish and reptiles have the ability to hold their eggs inside their bodies until they hatch. herring trout

15. Typically large numbers of eggs are laid at one time (an adult female cod can produce 4–6 million eggs in one spawning) because many will be eaten and not all will survive to hatch out into babies. The eggs are then left to develop without parental care. When the larvae hatch from the egg, they often carry the remains of the yolk in a yolk sac which continues to nourish the larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a critical point after which they must learn how to hunt and feed or they will die. skate shark

16. frogs newts Amphibian eggs are jellylike and are fertilized externally. They are soft shelled and need to be laid in water or protective foam or they would dry out. Water can pass through them to bring oxygen to the developing young. These eggs are often covered in a gooey jelly that protects them from diseases. Most amphibians lay hundreds or even thousands of eggs at a time, because many will be eaten and not all will survive to hatch out into babies.

17. The platypus and echidna (spiny anteater) are the only two egg-laying mammals in the world and they live in Australia. Monotreme eggs, which are laid out of water, are surrounded by a protective shell. The platypus has a bill like a duck, fur like a mammal, tail like a beaver and webbed feet. It lays eggs that look like reptile eggs. Its young feed from the mother's mammary glands. Echidna (spiny anteater) is a mammal that is covered with spikes and have long sticky tongues. They live in forests. The spiny anteater lays several eggs which it keeps in a pouch on its side. Mammal - a warm blooded animal that feeds its young milk. Monotreme - a mammal that lays eggs. Marsupial - a mammal that carries its young in an external pouch

18. oviparoushatcheggembryomammaleggshell fertilizeporousshellmonotremeoologyalbumen ovoviviparousbroodspawnyolkembryoincubation viviparousnourishnestfertilizemarsupialvertebrates

19. is there a difference in the size and number of eggs laid? do fish and amphibian eggs lay so many eggs while reptiles and birds lay just a few? While birds and reptiles are often able to build nests to camouflage and protect their eggs from predators, fish and amphibians' eggs are usually exposed to predators. For this reason, sometimes few eggs survive.

20. Which of these animals lay eggs? Point to each animal to learn if it does or it doesn’t. Hint: Some eggs can be tiny. Can you find at least one example from each type (class) of vertebrate (fish, reptile, amphibian, bird, and mammal)? echidnaplatypus rabbitdeerfrogfox spidersnake penguincowhenbird

21. fishfew days to months ( varies with breed) platypus7-14 days pigeon10-18 days ladybug21 days. chick21 days goose25-28 days duck26-28 days swan33-36 days ostrich42 days crocodilesup to 110 days turtles60-100 days ( varies with breed)