Tuesday, January 3, 2012

Wonders of creation: Portuguese Man o War

As an aspiring ecotheologian I spend a fair time worrying about the state of the planet, global warming, species loss, etc. It occurred to me recently that I don't spend enough time thinking about and enjoying the very thing I want to see looked after. This is the first in a series of blog entries featuring photos I've taken of things that have caught my eye.

Over Christmas 2011 my family and I stayed in the sleep village of Loch Sport, located along the 90 Mile Beach in the Lakes District of Gippsland (map here). I found a few of these Portuguese Man o War on the beach.

The Portuguese Man o War is also known as the Blue Bottle for obvious reasons. They are named Portuguese Man o War because the gas filled bladder looks like the sail of the ship of the same name. A Portuguese Man o War is not jelly fish but a member of the Siphonophorae order, a colonial animal consisting of different zooids or polyps which cannot exist independently.

The four polyps are the gas bladder (pneumatophore), the tentacles (which can reach up to 50 metres in length), the digestive organs and the reproductive organs. Note that the Portuguese Man o War is a carnivore, the tentacles are covered in venom-filled nematocysts which paralyse prey before muscles in the tentacles draw the prey up to the digestive organs. One of these tentacles is shown in the picture above and they can still contain venom even after the Man O War has died and is washed up on the beach, so avoid contact. While rarely fatal to humans, they are (apparently) very painful, and I was sure that myself, son and dog avoided them. In Australia there are more than 10,000 reported stings each year!

Their range is typically more equatorward than where I found these, preferring warmer waters. With no means of propulsion, the Man O War is at the mercy of wind and waves, so perhaps the warm current along the east coast of Australia moved them southward before becoming beached where I found them.

Further reading
National Geographic
Jellyfish sting statistics