Photograph by Martin Oeggerli, National Geographic
Dryas iulia
Perched on the tendril of a Passiflora plant, the egg of the Julia heliconian butterfly may be safe from hungry ants. This species lays its eggs almost exclusively on this plant’s twisted vines.
Eggs released into the water by mussels for fertilisation send out a chemical message that tells sperm they are a compatible mate, say researchers.
Evolutionary biologist Dr Jonathan Evans, from University of Western Australia, and colleagues, report their findings today in the Proceedings of the Royal Society B.
“The business of finding an egg is not as straight forward as you think it would be,” says Evans.
Mussels, like other marine invertebrates that are not mobile, release eggs and sperm into the water and these gametes must then find each other.
“These things are fixed to a rock. Their sperm and eggs go into a turbulent marine environment and they need some kind of clever mechanism to find each other,” says Evans.
It is known that many species release chemical clues to attract sperm to fertilise them - a process known as ‘sperm chemotaxis’.
-anna salleh
an eggshell has nearly 8000 pores that allow oxygen to flow in and carbon dioxide to flow out, allowing the chick to breathe.
