Probably best to stick to chocolate this Sunday
Trouts hatch before they can swim
When a female trout is ready to breed, she uses her tail to dig a trench called a redd in the gravelly riverbed. She lays her eggs in the redd and males fight for access, the winner releasing his sperm to fertilise them. Hatchlings can’t swim initially, staying put and feeding on their egg yolks until they’re ready.
Loggerheads remember the way home
Loggerhead sea turtles breed every two to four years, with females travelling hundreds of miles back to the beach they were born on. Here, they lay over 100 eggs in a nest and can produce six nests in a season before returning to the sea, leaving their young to dig their way out and dash for the ocean.
Catshark eggs are the stuff of legend
Also known as the small-spotted catshark, this small shark produces offspring two at a time. These are protected in egg cases with long tendrils to anchor them in place in the shelter of seaweed while they develop. After they’ve hatched, the cases wash up on beaches from Norway and the UK to North Africa and are known as ‘mermaid’s purses’.
Female Nile crocodiles are ferocious guards
Female Nile crocodiles dig holes in sand or earth near riverbanks and lay up to 80 eggs before guarding them for their three-month incubation. The sex of the young depends on the temperature during the middle month – within a narrow range males develop, while anything higher or lower results in females.
Egg shape is crucial for owl butterflies
The purple owl butterfly begins life in a tiny ribbed egg – this structure allows air in but prevents the developing insect from drying out. Once it hatches, the caterpillar immediately begins eating so that it has enough energy to transform into a large, vibrant adult ready to mate and continue the cycle.
Corn snakes fend for themselves
The corn snake, a species of rat snake, is a native of the US and Mexico. After temperatures cool for winter the snakes will court and mate and, a month later, females lay leathery eggs in warm, concealed spots then leave. A young snake uses its egg tooth – a modified scale – to break out of the egg.