Arenicolidae is a
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of marine
polychaete
Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...
worms. They are commonly known as lugworms and the little coils of sand they produce are commonly seen on the beach. Arenicolids are found worldwide, mostly living in burrows in sandy substrates. Most are
detritivore
Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...
s but some graze on
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
.
Description
The arenicolids are characterised by an elongated cylindrical body separated into two or three distinct regions. The
prostomium
The prostomium (From Ancient Greek, meaning "before the mouth"; plural: prostomia; sometimes also called the "acron") is the cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not include) th ...
has no
appendage
An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body.
In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...
s or
palp
Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") ...
s. There are one or two anterior segments without
setae
In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms.
Animal setae
Protostomes
Annelid setae are stiff bristles present on the body. Th ...
. On the other segments, all the setae are unbranched, including the capillary setae and the
rostrate uncini. The
notopodia
In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...
are bluntly truncate and the
neuropodia
In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...
are elongated tori forming long transverse welts in some of the setigers. The
notosetae have either a capillary function or act as limbs and the
neurosetae are rostrate hooks. There are
branchiae present on some of the setigers in the middle or posterior regions.
The Polychaete Worms
/ref> Apart from the genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
'' Branchiomaldane'', the lugworms are not easy to confuse with other polychaetes. Their tough cuticle and their distinct branchial region with strongly tufted branchiae are characteristic.
Classification
The family Arenicolidae contains 4 genera and 24 species.[
* '' Clymenides''
* '']Eruca
''Eruca'' is a genus of flowering plants in the family Brassicaceae, native to the Mediterranean region, which includes the leaf vegetable known as arugula or rocket.
The number of species is disputed, with some authorities only accepting a sin ...
''
* '' Protocapitella''
See also
* '' Arenicola marina''
* '' Abarenicola pacifica''
References
External links
{{Taxonbar, from=Q2860840
Polychaetes
Taxa named by George Johnston (naturalist)
Annelid families