Hydrothermal Vent and Cold Seep Worms: Vestimentifera

views updated

HYDROTHERMAL VENT AND COLD SEEP WORMS: Vestimentifera

HYDROTHERMAL VENT WORM (Riftia pachyptila): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Hydrothermal vent and cold seep worms have long, wormlike bodies reaching up to 9.8 feet (3 meters) in length. They live in whitish to gray-brown tubes at least as long as their bodies and are attached to hard surfaces on the ocean bottom. The tubes are made of chitin (KYE-tehn), a material similar to fingernails that makes up the external skeletons of insects, spiders, and their relatives. Most of the green to brown body remains inside the tube except featherlike structures, or plumes, and a pair of winglike flaps forming a collar that protects the head region. Special glands inside the flaps may produce the material used to make the tube. Bright red plumes surround the flaps. When threatened, the plumes are quickly withdrawn inside the tube. The plumes and blood vessels along the body are red because they are filled with blood containing a protein called hemoglobin (HE-meh-GLO-bihn). Hemoglobin captures oxygen from the water, helping these worms to breathe under water.

All hydrothermal vent and cold seep worms lack mouths or digestive tracts as adults. Like beard worms, they rely on the bacteria inside them for food. The body trunk is filled with reproductive organs. The segmented tail has a row of hooks that firmly anchor the body inside the tube.

GEOGRAPHIC RANGE

Hydrothermal vent and cold seep worms are found on the ocean bottom at the east Pacific Rise, mid-Atlantic Ridge, Galápagos Rift, Okinawa Trough, Mariana Trough, and the Lau, Manus, and North Fiji Basins. They also live along the continental margins of North and South America, Spain, and in the Mediterranean Sea.

HABITAT

Hydrothermal vent and cold seep worms live mostly in deep-sea waters, usually at depths greater than 0.6 miles (1 kilometer). They live along earthquake faults, or trenches, along the ocean floor. Some species attach their tubes to the chimneylike openings around deep-sea geysers called hydrothermal vents. Relatively warm water of 68°F (20°C) bubbles up through these vents. Others build their tubes near coldwater vents known as seeps. A few species are found only on whale carcasses that have settled deep on the ocean bottom.

DIET

Hydrothermal vent and cold seep worms live in total darkness. They rely on the billions of bacteria living in their bodies to make food. The worms provide the bacteria with carbon dioxide from their own bodies and hydrogen sulfide collected from the hydrothermal vents. As the bacteria convert these chemicals into energy for themselves, they produce simple sugars and other compounds that the worms absorb as food. The conversion of chemical reactions into food is called chemosynthesis (KEY-moh-SIN-thuh-sihs).

BEHAVIOR AND REPRODUCTION

Hydrothermal vent species mature within a few years, but those living near cold seeps may take 100 years or more to reach adulthood.

There is no contact between males and females. Males release sperm or sperm packets into the water, and the sperm find their way into the tubes of the females. Large numbers of eggs are fertilized inside or just outside the female's reproductive ducts and released into the water. The young larvae (LAR-vee) swim with the help of a band of hairlike cilia (SIH-lee-uh) on the front of their bodies. In order to feed, the larvae take in bacteria that eventually settle in their bodies as they grow. These mutualistic (MYU-chu-eh-LIH-stihk) organisms benefit from their relationship with each other.

HYDROTHERMAL VENT AND COLD SEEP WORMS AND PEOPLE

Scientists refer to hydrothermal vent and cold seep worms as "flagship" animals for deep sea habitats, especially deep-sea geysers known as hydrothermal vents. This means that these species have special appeal to people because of their beauty and may convince people to save the habitats where they and other animals live.

GUTLESS WONDERS

Hydrothermal vent and cold seep worms survive in short-lived habitats that are constantly appearing and disappearing. They must settle quickly to establish themselves and build up their numbers. Yet, they must also be able to distribute themselves over considerable distances to take advantage of new tube-building sites. How they manage to achieve both goals is still a mystery!

CONSERVATION STATUS

These worms are not considered endangered or threatened.

HYDROTHERMAL VENT WORM (Riftia pachyptila): SPECIES ACCOUNT

Physical characteristics: This species is the largest of the hydrothermal vent and cold seep worms. They reach up to 9.8 feet (3 meters) long, live in white tubes, and resemble giant lipsticks with their bright red plumes. Their protective flaps are white.

Geographic range: Hydrothermal vent worms live on the East Pacific Rise, Galápagos Rift, and Guayana Basin.

Habitat: These worms are found at depths of about 1 mile (1.5 kilometers) on hydrothermal vents.

Diet: Hydrothermal vent worms rely on bacteria and chemosynthesis for food.

Behavior and reproduction: These worms form dense colonies on hydrothermal vents. One of the fastest-growing marine animals, they build tubes up to 4.9 feet (1.5 meters) and reach adulthood in only 18 months.

Males release sperm into the water. Females also release fertilized eggs. The larvae are capable of spreading out to new hydrothermal vents.

Hydrothermal vent worms and people: They are "flagship" animals for hydrothermal vents and may help to conserve these habitats.

Conservation status: Hydrothermal vent worms are not considered endangered or threatened. ∎

FOR MORE INFORMATION

Books:

Gage, J. Deep-Sea Biology. A Natural History of Organisms at the Deep-Sea Floor. Cambridge, U.K.: Cambridge University Press, 1991.

Van Dover, C. L. The Ecology of Deep-Sea Hydrothermal Vents. Princeton, NJ: Princeton University Press, 2000.

Periodicals:

Fisher, C. R., I. A. Urcuyo, M. A. Simpkins, and E. Nix. "Life in the Slow Lane: Growth and Longevity of Cold-seep Vestimentiferans." Marine Ecology-Pubblicazioni della Stazione Zoologica di Napoli 18 (1997): 83-94.

Jones, M. L. "Riftia pachyptila Jones: Observations on the Vestimentiferan Worm from the Galápagos Rift." Science 213 (1981): 333-336.

Lutz, R. A., and R. M. Haymon. "Rebirth of a Deep Sea Vent." National Geographic (November 1994) 186, no. 5: 114-126.