Giant Fire Pyrosome, Pyrostremma spinosum
Giant Fire Pyrosome, Pyrostremma spinosum. Two photographs of a “chunk” collected at the time of the encounter in coastal waters off Point Palmilla, Baja California Sur, March 2018.
Giant Fire Pyrosome, Pyrostremma spinosum. Small cluster photographed three hours after collection in a controlled environment.
Giant Fire Pyrosome, Pyrostremma spinosum. One gallon of densely packed animal in salt water that was frozen for storage and later study. Identification courtesy of Linsey Sala, Scripps Institution of Oceanography, La Jolla, California.
The Giant Fire Pyrosome, Pyrostremma spinosum (Hardman, 1888), is a member of the Pyrosomatidae Family of Pyrosomes. They are one of the world’s true exotics and found in all of the open oceans in warm tropical and temperate waters. They are ginormous in size and seldom seen by humans.
The Giant Fire Pyrosome is known for its large colony size and can be up to 20 m (65 feet) in total length and 1.2 m (4 feet) in diameter. They are soft, opaque and are either transparent (feeding stage) or reddish-pink (agitated stage) in color. The initial colonies are semi-globular and dome-shaped with a thick opaque test. As they mature, the colonies become cylindrical or cone-shaped being composed of hundreds of thousands of individuals known as zooids all connected via sharing tissues. Each massive colony originates from a single zooid that rapidly multiplies via cloning into a meshed colony growing outwards in concentric circles. Each zooid is a few millimeters in size but embedded in a common gelatinous tunic that is similar to a butterfly net with a wide mouth that tapers to a closed end that joins all individuals. The zooids have the ability to regenerate damaged areas.
The Giant Fire Pyrosomes are normally found at depths between 460 m (1,500 feet) and 3,000 m (10,000 feet). Their zooid is exposed to the ocean water both on the inside and the outside of the “tunic” and feed as filter feeders that take in water through a mouth on the outside of the body, pass it through a filtration system removing microscopic phytoplankton and small microzooplankton and oxygen, and then they expel it on the inside of the cone. They are planktonic with movements largely controlled by oceanic currents, tides and waves but are generally found far out at sea where the mineral balance is better and their food source is smaller and thus more digestible. They are vertical migrators moving up in the water column by generating a water stream by feeding to feed during the night and retreating to depths to avoid predation during daylight hours. They lack any common nerves for communication and they communicate via an ability to produce light, which travels through the colony in waves with each individual zooid producing light that can be seen from several meters. They also provide homes for Commensal Shrimp, and other crustaceans often found riding inside these animals. The Giant Fire Pyrosome is are preyed upon by Sea Turtles and the Ocean Sunfish, Mola mola. When under attack, disturbed or under stress they “light up”, changing from a transparent white to a pinkish red and they stop feeding. This allows them to sink down too much greater depths in the water column for safety. They have life spans that are directly dependent upon physical disturbance and the correct nutrient levels in the water in which they live and related food availability.
The Giant Fire Pyrosome is a straightforward identification that cannot be confused with any other species.
In Mexican waters the Giant Fire Pyrosome range is poorly documented but they are assumed to be present in all waters of both the Atlantic and the Pacific Ocean.
Synonyms include Propyrosoma spinosum, Pyrosoma excelsior, Pyrosoma sedentarum and Pyrosoma spinosum.
Details on the Encounter. On April 12, 2018, I was fishing in 105 m (350 feet) water in a traditional Mexican Panga in coastal waters just south of San José del Cabo, Baja California Sur, about 3 miles due south of the Los Cabos Westin (23.00oN, 113.00oW). I observed something large in the water, about the size of our 7 m (22 feet) Panga, that was pink in color. The call from my very knowledgeable Captain was “a large piece of plastic.” I asked him to have a closer look. We slowly inched closer and I saw a 180 kg (400 lb) sea turtle depart. He apparently had brought this long ribbon-like pink “sheet” to the surface on which he had been munching away. The turtle split and I grabbed whatever it was with a paw. It was a gelatinous goo composed of perhaps tens of billions of identical appearing individuals all linked together. We estimated its total size to be 8 inches by 14 feet as it slowly sank out of view. I was able to break off a portion very easily, that was perhaps 8 inches by 2 feet. See photograph above. Unfortunately I failed to get an on-site photo of the intact animal as it quickly sunk out of sight.
An excellent video of this species is available on YouTube that was taken in Australian waters. You can see it at the at the beginning of https://www.youtube.com/watch?v=5EQGA_4BZ5s.