Dead-Man’s Fingers Algae
Codium fragile
Dead-man’s fingers are small seaweeds that originated in Japan but are now found worldwide. They have different reproduction options available and can be easily introduced in a new environment. These algae are considered an invasive species because of how they become the dominant plant species in areas where they are not native. Though they have natural predators like snails, they are not the snails’ preferred food due to the algae’s taste. However, there are some places on the planet where this algae is eaten regularly by humans!
SPECIES IN DETAIL
Dead-Man’s Fingers Algae
Codium fragile
CONSERVATION STATUS: Invasive Species
CLIMATE CHANGE:
Geographic Distribution
These algae are native to Japan’s coastal regions and have been introduced to every other continent. They can be found growing along the coasts of Southwest Africa, Australia, Southern Argentina, Chile, China, Denmark, England (particularly the British Isles), Ireland, Korea, as well as the Atlantic and Pacific coasts of North America, Norway, Netherlands, New Zealand, Scotland, and Sweden.
Habitat
They are found year round at open coasts, estuaries, tide pools, and intertidal and subtidal zones. They attach to rocks, shells, and other hard substrates. Dead-mans fingers can be found in sheltered habitats such as bays and harbors. They are able to grow in shallow coastal waters up to 15 meters in depth.
Physical Characteristics
The dead-man’s fingers algae are dark green in color with a texture that feels soft and felt-like. Their branches look like swollen fingers that float in the water or lie on rocks and cliffs at low tide. The branches are thick and spongy, Y-shaped, and cylindrical. The branches grow to 3 to 10 millimeters in diameter.
Size
These algae can grow 39—90 centimeters (15—35 omches) and weigh up to 3 kilograms (6.61 pounds) per plant.
Diet
They gain nutrients through photosynthesis (converting energy from sunlight).
Reproduction
Dead-man’s fingers algae reproduce in three ways: sexual reproduction, parthenogenetically, and asexually. First, with sexual reproduction, the male and female gametes are both produced on separate plants. Each of the gametes has two flagella, and the female gametes are larger than the male gametes. Second, they reproduce parthenogenetically where the female gamete develops into a new individual without fertilization. Third, this algae reproduces asexually, forming a genetically identical individual from a branch or stem of the parent plant.
Behavior
Dead-man’s fingers are considered an invasive species. They can be found wrapped around places like dock pilings. They use their roots and branches to wrap around shells, so much so that they can even stop the invertebrates inside from moving and may even dislodge them completely! This algae is likely to displace the native seagrasses and seaweed due to its fast growth.
Adaptation
These algae are highly adaptive and can survive nearly everywhere. They thrive in areas with little sunlight, can rely on nitrogen reserves for nutrients when conditions are not favorable (in areas or in seasons of limited resources in the environment), and have many ways of reproducing. These adaptations enable it to quickly overgrow in areas like oyster beds and outcompete native species.
Conservation
These algae are seen as a pest. They are able to replace native seaweeds such as kelp and seagrasses as the dominant seaweed. They have annihilated the kelp beds off the North Atlantic, off the coast of Nova Scotia, and Maine. Because Codium bushes do not offer the same resources as Kelp forests, in areas where it is replacing Kelp, traditional communities give way to a Codium-dominated ecosystem.
Special Notes
At one time dead man’s fingers were used as packing material for shipping live marine invertebrates! They are eaten by humans in some cultures. They are used to feed various species of invertebrates in the mariculture industry.
SPECIES IN DETAIL | Print full entry
Dead-Man’s Fingers Algae
Codium fragile
CONSERVATION STATUS: Invasive Species
CLIMATE CHANGE:
These algae are native to Japan’s coastal regions and have been introduced to every other continent. They can be found growing along the coasts of Southwest Africa, Australia, Southern Argentina, Chile, China, Denmark, England (particularly the British Isles), Ireland, Korea, as well as the Atlantic and Pacific coasts of North America, Norway, Netherlands, New Zealand, Scotland, and Sweden.
They are found year round at open coasts, estuaries, tide pools, and intertidal and subtidal zones. They attach to rocks, shells, and other hard substrates. Dead-mans fingers can be found in sheltered habitats such as bays and harbors. They are able to grow in shallow coastal waters up to 15 meters in depth.
The dead-man’s fingers algae are dark green in color with a texture that feels soft and felt-like. Their branches look like swollen fingers that float in the water or lie on rocks and cliffs at low tide. The branches are thick and spongy, Y-shaped, and cylindrical. The branches grow to 3 to 10 millimeters in diameter.
These algae can grow 39—90 centimeters (15—35 omches) and weigh up to 3 kilograms (6.61 pounds) per plant.
They gain nutrients through photosynthesis (converting energy from sunlight).
Dead-man’s fingers algae reproduce in three ways: sexual reproduction, parthenogenetically, and asexually. First, with sexual reproduction, the male and female gametes are both produced on separate plants. Each of the gametes has two flagella, and the female gametes are larger than the male gametes. Second, they reproduce parthenogenetically where the female gamete develops into a new individual without fertilization. Third, this algae reproduces asexually, forming a genetically identical individual from a branch or stem of the parent plant.
Dead-man’s fingers are considered an invasive species. They can be found wrapped around places like dock pilings. They use their roots and branches to wrap around shells, so much so that they can even stop the invertebrates inside from moving and may even dislodge them completely! This algae is likely to displace the native seagrasses and seaweed due to its fast growth.
These algae are highly adaptive and can survive nearly everywhere. They thrive in areas with little sunlight, can rely on nitrogen reserves for nutrients when conditions are not favorable (in areas or in seasons of limited resources in the environment), and have many ways of reproducing. These adaptations enable it to quickly overgrow in areas like oyster beds and outcompete native species.
These algae are seen as a pest. They are able to replace native seaweeds such as kelp and seagrasses as the dominant seaweed. They have annihilated the kelp beds off the North Atlantic, off the coast of Nova Scotia, and Maine. Because Codium bushes do not offer the same resources as Kelp forests, in areas where it is replacing Kelp, traditional communities give way to a Codium-dominated ecosystem.
At one time dead man’s fingers were used as packing material for shipping live marine invertebrates! They are eaten by humans in some cultures. They are used to feed various species of invertebrates in the mariculture industry.