Dead man's finger
Dead man's fingers are a type of coral belonging to the genus Alcyonium, commonly found in deep coastal waters of the Mediterranean Sea and the North Atlantic Ocean. Their distinctive name derives from their resemblance to a human hand, with finger-like lobes and a pale flesh color. These corals typically attach to the ocean floor, often found on pebbles and bivalve shells, and can grow in waters ranging from 45 to 90 feet deep. The size of dead man's fingers varies with depth; specimens in shallow waters are generally smaller due to stronger currents.
Dead man's fingers are colonial organisms made up of individual polyps that resemble tiny sea anemones, each equipped with stinging cells to capture prey such as zooplankton. They can reproduce both asexually, through budding, and sexually by releasing gametes into the water. The larvae then seek suitable places to establish new colonies. Threatened by climate change and rising sea temperatures, the lifespan of dead man's fingers typically ranges from 10 to 15 years, though some colonies can survive up to 20 years. These fascinating creatures play a vital role in their marine ecosystems but face significant challenges in the face of environmental changes.
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Dead man's finger
Dead man's fingers were given their name by sailors because they are about the size of a man's hand, have finger-sized lobes, and are often a pale flesh color. Dead man's fingers were also referred to as dead man's toes, depending on the size of the specimen.
Kingdom: Animalia
Phylum: Cnidaria
Class: Octocorallia
Order: Alcyonacea
Family: Alcyoniidae
Genus: Alcyonium
Species: Digitatum
Dead man's fingers are typically found in the deep coastal and warm temperate waters of the Mediterranean Sea and North Atlantic Ocean. They are often attached to pebbles and bivalve shells along the ocean floor. Bivalve shells are the shells of creatures like oysters and clams made of two joined shells.
Dead man's fingers can be found in waters as shallow as 45 feet (15 meters) or as deep as 90 feet (30 meters). In shallow waters, dead man's fingers are smaller than in deep waters because of the shallow water's constant current. As they grow, they are eventually tipped over by the current and buried in the sand.
Dead man's fingers found in depths of 45 to 60 feet (15 to 20 meters) are between 1 1/2 and 2 inches (4 and 5 centimeters) long when removed from the water while dead man's fingers found at depths of 60 to 90 feet (20 to 30 meters) are generally 3 to 4 inches (7 1/2 to 10 centimeters) long when pulled from the water. All dead man's fingers expand when in the water and contract when removed from the water.
Dead man's fingers were given their name for their likeness in size, shape, and color to a dead man's fist. Each of the lobes of the coral appears as fingers, while the coral's pale flesh tone gives it a resemblance to skin.
Like other coral, dead man's fingers live in orange, yellow, or white colonies of individual coral polyps. These polyps look like tiny sea anemones with tentacles in sets of eight. These tentacles have stinging cells called nematocysts. These small cells stun aquatic, or water-living, prey like zooplankton and phytoplankton. Once paralyzed, prey is pulled into the polyp, and the nutrients are shared by the entire colony. Sea slug species and sea spiders (Pycnogonum litorale) prey on dead man's fingers.
Dead man's fingers can reproduce by asexual and sexual reproduction. Asexual reproduction, or reproduction involving only one organism, is done in the form of budding. As the colony grows, new buds, or individual polyps, are formed on the lobes, or fingers, of the coral. This is how dead man's fingers use asexual reproduction. Sexual reproduction involves growing reproductive cells, called gametes, in December or January. Nearly a year later, the eggs and sperm are released into the water. This type of reproduction helps create new dead man's finger colonies, which can reach nearly 8 inches (20 centimeters) in height and width. The eggs and sperm join and form free-swimming dead man's fingers larvae. Each larva searches for an appropriate place to create a new colony. After about one week, the embryo settles and develops into a polyp. Buds, or new polyps, eventually form on that first polyp, beginning the new colony.
Because dead man's fingers depend on coral, their population is threatened by climate change as sea levels and temperatures rise.
The life span of dead man's fingers is 10 to 15 years though some colonies have lived 20 years.
Bibliography
"Dead Man’s Fingers." Ocean Info, oceaninfo.com/animals/dead-mans-finger. Accessed 5 Apr. 2024.
"Dead Man’s Fingers." Ocean, Smithsonian Museum of Natural History, ocean.si.edu/ocean-life/invertebrates/dead-mans-fingers. Accessed 5 Apr. 2024.