Suddenly Something Completely Unexpected in the Middle of the Atlantic – A Giant Pyrosome

World-renowned underwater photographers Göran Ehlmé and Nuno Sá are diving off the island of St. Maria in the Azores when they suddenly spot something completely unexpected.

They have both dived in almost every ocean in the world, among whales, sharks, manta rays, walruses and orcas, but have never seen anything like this.

What is floating in the water? Something large, orange and tube-shaped. My Ehlmé Tange is part of the expedition and takes the opportunity to take some incredibly beautiful pictures of the creature, or creatures, because there are many of them.

This fascinating creature is called  Pyrostremma spinosum.

^{Text and Photo: My Ehlmé Tange}

Pyrostremma spinosum belongs to a genus of pelagic pyrosomes — free-floating colonial tunicates found in the open ocean. Each colony is made up of hundreds to thousands of small, individual organisms called zooids.

These creatures are planktonic filter feeders, meaning they drift with ocean currents and feed on microscopic plankton by filtering water. Despite being individual organisms, the zooids are connected by tissue, allowing them to communicate and coordinate movements such as swimming, which enables the colony to slowly propel itself through the water.

Pyrosomes are hermaphroditic and reproduce through a complex two-stage process. Under favorable conditions, they can form massive blooms that may impact pelagic (open-ocean) food webs.

Colonies typically range from 20 to 50 cm in length, but specimens as long as 10 meters (with a diameter of up to 1.2 meters) have been observed — It can sometimes reach nearly 20 meters.

These organisms serve important ecological functions: they offer food, shelter, and settlement for other deep-sea species. Additionally, dead pyrosome colonies contribute to the marine carbon cycle by sinking to the seafloor, where they become a food source for other animals. Pyrosomes are consumed by sea turtles, fish, albatrosses, and even a species of sea lion.

They are most commonly found in the upper layers of warm and temperate circumtropical waters, though some species inhabit deeper parts of the ocean. Some pyrosome species have been shown to expand their geographic range in response to increasing ocean temperatures, which has unknown implications for the already existing ecosystems.