Pyrosome

Pyrosoma atlanticum

ORDER Pyrosomatida

FAMILY Pyrosomatidae

TAXONOMY

Pyrosoma atlanticum (Peron, 1804), Mediterranean Sea.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Individuals called zooids are about 0.33 in (8.5 mm) and embedded in a thick, clear tubular test that can reach 23.6 in (60 cm) in length. Colonies are pink or yellowish pink. The oral siphons of the zooids are on the outer surface of the tube and the cloacal siphon point to the inside. Water comes in the oral siphon and empties into the common opening inside of the tube. One end is closed and the water exits out a common opening at the other end of the colony, propelling it through the water. Each of the zooids is brilliantly bioluminescent and this is the reason for the scientific name of pyrosoma, "fire body."

DISTRIBUTION

Semi-cosmopolitan in temperate to tropical waters, it is the most common pyrosome. (Specific distribution map not available.)

HABITAT

Commonly seen in surface waters, but daily vertically migrates more than 2,460 ft (750 m).

BEHAVIOR

Known for the brilliant luminescence of each zooid, communication among zooids results in waves of light along the entire colony.

FEEDING ECOLOGY AND DIET

Water passes into each zooid through the oral siphon, into a mucous filter where phytoplankton is filtered out for food. Py-rosomes can form huge swarms that can result in significant quantities of fecal pellets. The sinking pellets can be very important in carbon input into the depths.

REPRODUCTIVE BIOLOGY

Zooids are hermaphrodites, possessing both testis and ovary. In each zooid of the colony a single egg is fertilized, which grows to a four-zooid stage that leaves the parent to start a new colony asexually by budding. This form of reproduction can result in huge swarms of pyrosome colonies that are dependent upon abundant phytoplankton for food.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

The brilliant light displays given off from colonies of pyro-somes have bewildered and fascinated sailors for generations.4

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Responses

  • kathrin
    What is the scientific name or a pyrosome?
    5 years ago

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