Arenicolidae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of marine

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

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 ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

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"; : prostomia; sometimes also called the "acron") is the Cephalization, cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not in ...

has no

appendage An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...

s or

palp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicera ...

s. There are one or two anterior segments without

setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae ...

. On the other segments, all the setae are unbranched, including the capillary setae and the rostrate uncini. The

notopodia In invertebrates, the term parapodium (Greek language, Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in Annelid, annelids, where they ar ...

are bluntly truncate and the neuropodia 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. Apart from the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' 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. * '' Abarenicola'' – 11 species * '' Arenicola'' – 7 species * '' Arenicolides'' – 2 species * '' Branchiomaldane'' – 4 species There are also three uncertain genera. * '' Clymenides'' * '' Eruca'' * '' Protocapitella'' Fossil traces indicate that the group has existed since at least the Late Jurassic.

References

{{Authority control Polychaetes Taxa named by George Johnston (naturalist) Annelid families

Description

Classification

See also

References