BWB – Sailing colonies

Siphonophores are fascinating sea creatures are often confused with jellyfish. They are not a single creature, but complex colonies of specialised individuals. So-called polyps or medusoids live together in a division of labour. Each unit performs a specific task, such as locomotion, feeding or reproduction.

The Portuguese man o’ war (Physalia physalis) is a well-known example of a Siphonophores. It has long, poisonous tentacles with which it catches small fish and other sea creatures. Its beautiful gas-filled floating body allows it to float on the surface of the water. They feed using specialised tentacles that are covered with cnidocytes to paralyse their prey. In addition to the Portuguese man o’ war, we often see the By-the sea salor off Madeira’s coast.

Siphonophores can grow to several metres in length. Some species, such as the Praya dubia, are among the longest known marine animals – they can reach up to 40 metres! Despite their impressive size, they are very fragile as they are made of soft tissue. These organisms often move passively with the ocean currents or use pulsating movements of their medusoids to move around. Siphonophores are fascinatingly beautiful and can be dangerous to humans. Contact with the nettles of the Portuguese man o’ war can lead to painful injuries that can even be life-threatening.

The unusual way of life of Siphonophores makes them an exciting object of research in marine biology. Scientists are studying their unique organisation and impressive abilities to learn more about colonial life forms and the evolution of complex organisms.

By Fatima Kutzschbach