Bloodworms (Glycera dibranchiata) are a type of annelid, or segmented worm, like an earthworm. Unlike earthworms, they’re found in marine habitats where they burrow into the silt and sand—a good position for keeping a low profile from predators and staking out prey.

Bloodworms are carnivorous (although they consume detritus when needed) and will extend a long proboscis from their heads with venom-bearing jaws for grasping prey. Its venom is generally not delivered in a quantity dangerous to humans, but they can produce a bite that stings.

Their jaws have been interesting to scientists due to the high amounts of copper present in them, which had previously not been seen in a living organism. This unusual trait has potential for helping bioengineers develop new possibilities in materials science.

The bloodworm can be found in the intertidal area of coastal marine and estuarine environments where they might be scooped up by seagulls, crabs, or bottom-feeding fish, down to depths of 24 meters (79 feet) or more. They are most often located in the benthic zone and in areas where the sediments are soft enough for burrowing.

The species shown here, Glycera dibranchiata, ranges from the shores maritime provinces of eastern Canada, down along the east coast of the United States and south along the shores of the Gulf of Mexico and the Caribbean Sea. Bloodworms are commonly harvested and used as fishing bait.

  1. What role do scientists hypothesize that the copper plays in the jaws of the venomous bloodworm?

    • Answer

      Scientists who have studied the bloodworm hypothesize that the copper present in the jaws of a bloodworm help protect it against abrasion from sand and gravel that the bloodworm’s jaws may come into contact with when it is attempting to capture its prey; it also provides strength to the overall jaw for piercing into prey to release its venom.

  2. What other animals besides the bloodworm have a proboscis as a mouth part?

    • Answer

      A proboscis refers to a tubular mouthpart or simply a long snout, as in the trunk of an elephant. There are many examples of invertebrates that have very defined proboscis for feeding, including butterflies, mosquitos, and marine snails. Mammals such as echidnas, anteaters, and elephant shrews also have an elongated nose structure that can be called a proboscis.

  3. Although the bloodworm hunts for prey, it has been observed consuming detritus, as well. What is an animal called that feeds exclusively or nearly exclusively on detritus?

    • Answer

      Detritus is dead plant and animal and fecal matter. In the benthic zone, there are many organisms that feed exclusively on this. They are called detritivores and they make up an essential part of the food chain.


large phylum consisting of segmented worms, including terrestrial, marine, and freshwater species.

benthic zone

the floor of a body of water.


organism that eats meat.


non-living organic material, often decomposing.


having to do with an estuary.


having to do with the ocean.


animal that hunts other animals for food.


animal that is hunted and eaten by other animals.


long, narrow mouthpart used by many insects for piercing and sucking.