Glycera (genus)

Bloodworms
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Glycera sp.
Scientific classification
Kingdom:	Animalia
Phylum:	Annelida
Class:	Polychaeta
Order:	Phyllodocida
Family:	Glyceridae
Genus:	Glycera Savigny, 1818
Species
many, see text

The genus Glycera is a group of polychaetes (bristle worms) commonly known as bloodworms. They are typically found on the bottom of shallow marine waters, and some species (e.g. the common blood worm, Glycera dibranchiata), are extensively harvested along the Northeastern coast of the United States for use as bait in fishing. Another common species is the tufted gilled bloodworm, G. americana.

Anatomy

Bloodworms have a creamy pink color, as their pale skin allows their red body fluids that contain hemoglobin to show through. This is the origin of the name "bloodworm". At the 'head', bloodworms have four small antennae and small fleshy projections called parapodia running down their bodies. Bloodworms can grow up to 35 centimetres (14 in) in length.

Ecology

Bloodworms are poor swimmers but good burrowers, living on the sandy or silty bottoms of the intertidal or subtidal regions. Though usually marine, they can tolerate low salt levels in the water, and also poor oxygen levels. Bloodworms and all water worms have adapted to life in the sand and silt for the protection it offers.

Bloodworms are carnivorous. They feed by extending a large proboscis that bears four hollow jaws. The jaws are connected to glands that supply poison which they use to kill their prey, and their bite is painful even to a human. They are preyed on by other worms, by bottom-feeding fish and crustaceans, and by gulls.

Reproduction occurs in midsummer, when the warmer water temperature and lunar cycle among other factors triggers sexually mature worms to transform into a non-feeding stage called the epitoke. With enlarged parapodia, they swim to the surface of the water where both sexes release gametes, and then die.

The first stage in many forms of bloodworm is a zooplanktonic stage followed by the benthic instar where the familiar segmented red larvae develop protected by silk tubes made in the bottom silt. These larvae progress from tiny pale opaque worms to the larger red larvae of 3 to 10 centimeters in length or longer over a period of as short a period as 2 – 3 weeks in optimum conditions.

The animals are unique in that they contain a lot of copper without being poisoned. Their jaws are unusually strong since they too contain the metal in the form of a copper-based chloride biomineral, known as atacamite. And unlike the clamworm (Nereis limbata), whose jaws contain the metal zinc, the copper in the mineral in the jaws of Glycera is actually present in its crystalline form. It is theorized that this copper is used as a catalyst for its poisonous bite.

Systematics

Glycera is the type genus of the family Glyceridae. It contains the following species:

Glycera abranchiata Glycera alba Glycera amadaiba Glycera amboinensis Glycera americana Glycera asymmetrica Glycera baltica Glycera bassensis Glycera benguellana Glycera benhami Glycera branchiopoda Glycera brevicirris Glycera calbuconensis Glycera capitata Glycera carnea Glycera celtica Glycera chirori Glycera cinnamomea Glycera convoluta Glycera dayi Glycera decipiens Glycera dentribranchia Glycera derbyensis Glycera dibranchiata

Glycera dubia Glycera edwardsi Glycera ehlersi Glycera embranchiata Glycera epipolasis Glycera fundicola Glycera fusiformis Glycera gigantea Glycera gilbertae Glycera glaucopsammensis Glycera guatemalensis Glycera guinensis Glycera hasidatensis Glycera heteropoda Glycera incerta Glycera kerguelensis Glycera knoxi Glycera lamelliformis Glycera lamellipodia Glycera lancadivae Glycera lapidum Glycera longipinnis Glycera longissima Glycera macintoshi

Glycera madagascariensis Glycera manorae Glycera martensii Glycera mauritiana Glycera micrognatha Glycera mimica Glycera minor Glycera minuta Glycera nana Glycera natalensis Glycera nicobarica Glycera nigripes Glycera onomichiensis Glycera orientalis Glycera oxycephala Glycera pacifica Glycera papillosa Glycera pilicae Glycera polygona Glycera posterobranchia Glycera prashadi Glycera profundi Glycera prosobranchia Glycera pseudorobusta

Glycera robusta Glycera rouxi Glycera russa Glycera rutilans Glycera spadix Glycera sphyrabrancha Glycera subaenea Glycera taprobanensis Glycera taurica Glycera tenuis Glycera tesselata Glycera unicornis

Use by humans

Glycera worms are sold commercially by nurseries and aquatic stores in live, frozen, and freeze dried form as a food for aquarium fish and frogs. They are also commonly sold in tackle shops as bait for saltwater fishing.

Possible allergic reactions

Some fish tank enthusiasts have reported mild to severe allergic reactions when handling (frozen or freeze dried) blood worms. Words of warning are included in some freeze dried products sold commercially. For example:

"For adult use only. Keep away from children - Warning: Allergy Alert! This product contains insect larvae which may cause allergic reaction in some individuals. If symptoms of allergic reaction occur (such as hives, asthma, wheezing, red or irritated eyes or skin, runny nose or sneezing), discontinue use immediately and consult your physician. Avoid all use if symptoms reoccur. Do not use this product if you suffer from asthma, high fever or are known to be allergic to insect larvae. Hobbyists and heavy users should use special precautions not to touch or breathe dust of product. Heavy users can potentially become sensitized to this product."

Some users have also reported allergic reactions even when touching the box the product has been shipped in. Therefore, it is recommended that these are kept away from children, and gloves are used while handling. Blood worm dust could be inhaled while feeding fish so it is best to avoid crushing them at all, or use the help of tweezers or a tool of some sort.

Popular culture references

• Dirty Jobs host Mike Rowe went digging for bloodworms in Maine in episode 5.2 from December 2006.
• The 1976 film Squirm featured bloodworms attacking the people of a small town.
• The novel Blood Worm by John Halkin, printed in 1988 features a giant bloodworm attacking citizens in England.
• In the classic Star Trek episode, "The Trouble With Tribbles," a drunken Klingon refers to Jim Kirk as a Regulan bloodworm.
• in the National Geographic show, "Filthy Riches", there are a pair of bloodworm collectors.

References

"Fishing for Allergens: Bloodworm-Induced Asthma" study at the Allergy, Asthma & Clinical Immunology (AACI) site

Multiple fish enthusiast forums reporting allergic reactions