Maldanidae is a family of more than 200 species of

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are mad ...

commonly known as bamboo worms or maldanid worms. They belong to the order

Capitellida Capitellida is an order of annelids belonging to the class Polychaeta. Families: * Arenicolidae Johnston, 1835 * Capitellidae Grube, 1862 * Maldanidae Maldanidae is a family of more than 200 species of Marine life, marine polychaetes commonly ...

, in the phylum Annelida. They are most closely related to family

Arenicolidae Arenicolidae is a family of marine polychaete 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 ...

, and together form the clade

Maldanomorpha Maldanomorpha is a monophyletic group, or clade, of polychaete worms in the phylum Annelida. Several phylogenetic analyses based on morphology (biology), morphological and molecular phylogeny, molecular data have shown that this clade unites the f ...

Morphology

Maldanid worms have a long and cylindrical body that usually bends at one or both ends. It can be divided into four parts: 1) a

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

, formed by a

dorsally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

positioned

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 ...

that is fused to the

peristomium The peristomium is the first true body segment in an annelid worm's body in the anterior end. It is directly behind the prostomium and contains the mouth, tentacular cirri, and sometimes feeding palps, which may instead occur on the prostomium. If ...

, sometimes with a flattened

cephalic A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

plate; 2) a

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

, formed by the first four chaetigers (i.e. chaetae-bearing segments), usually with strong spines; 3) an

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

, with several longer chaetigers that are often followed by a number of achaetous (i.e. without chaetae) segments; 4) a posterior end, with a

pygidium The pygidium (plural pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compo ...

that contains the

anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...

. The maldanid

takes a wide variety of forms such as conical, plate-shaped and funnel-shape. Sometimes a few prepygidial (i.e. anterior to the

) segments can be observed. The

parapodia 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 generally biramous, with elongated median chaetigers. The

notochaetae A chaeta or cheta (from Greek χαίτη “crest, mane, flowing hair"; plural: chaetae) is a chitinous bristle or seta found in annelid worms, (although the term is also frequently used to describe similar structures in other invertebrates such ...

appear as various forms of capillaries, while the

neurochaetae A chaeta or cheta (from Greek χαίτη “crest, mane, flowing hair"; plural: chaetae) is a chitinous bristle or seta found in annelid worms, (although the term is also frequently used to describe similar structures in other invertebrates such ...

appear as various forms of uncini (i.e. hook-like structures), sometimes replaced by acicular (i.e. needle-like) spines in some

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

segments.

Ecology

Habitat

Species of maldanid worms are distributed in all marine regions of

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

, from the intertidal regions to deep waters. Some species inhabit estuarine areas, and some species have been seen living on

hydrothermal vent A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspot ...

s. They are

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

creatures that build tubes made of mineral particles of diverse sizes and textures; these tubes are fixed to stones, shells, algal holdfasts, mud or sandbanks through a thin and transparent matrix of

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

that is produced after the end of the larval period. Several species build tubes under rocks forming horizontal galleries, or vertical galleris in sand or mud at the bottom of

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

Nutrition

They consume organic material, mostly composed of

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

, although

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

s and

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

ns have been seen in the gut of some species. Most of them are head-down feeders that transport sediments upward from below the ocean floor surface. However some species have been observed dragging surface material down their tube into a feeding cavity. During feeding, the worms extend a papillae-covered globular

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

through an increase of the

coelomic A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid. The two largest human body cavities are the ventral body cavity, and ...

pressure in the first four chaetigers. An enhanced

bacterial Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

growth observed within the tube wall of one species, '' Maldane sarsi'', might also be a source of nutrition. Another species, '' Praxillura maculata'', bears stiff particle-collecting spikes attached to the tube's end to collect

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 ...

and organic particles and transport them to the gut.

Reproduction

Maldanid worms are

gonochoristic In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism c ...

and present a variety of reproductive modes. Some species spawn their gametes into

seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...

, where fertilization occurs; others may incubate eggs in the tube or directly until the development of larvae. They are capable of both anterior and posterior regeneration after suffering damage due to their fragile and easily fragmented bodies, and at least one species that

reproduces asexually Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the fu ...

has been described.

Embryonic development

Like other invertebrates in the clade

Spiralia The Spiralia are a morphologically diverse clade of protostome animals, including within their number the molluscs, annelids, platyhelminths and other taxa. The term ''Spiralia'' is applied to those phyla that exhibit canonical spiral cleavage, a ...

, bamboo worms undergo

spiral cleavage In embryology, cleavage is the division of cells in the early development of the embryo, following fertilization. The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size ...

during their early development. The larvae have a prototroch, neurotroch and

telotroch Telotroch is the free-swimming stage of members of the order Sessilida. Sessilida are ciliates of the subclass Peritrichia. A sessile individual can turn into a motile one to migrate to a better place.polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are mad ...

. The larval period is short, and the larval development is either

lecithotrophic Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and mo ...

(i.e. with a yolk sac attached for nutrition) or direct (i.e. having to feed independently).

Phylogeny

Maldanidae and

are united by the clade

inside of

, an order of

in the phylum Annelida. According to a

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

based on morphological data from 2011, several of the subfamilies inside Maldanidae are united under a clade called 'Maldanoplaca'. Members of this clade would be united by the evolution of the

into an anal plate. However, a

molecular phylogeny Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

in 2018 reveals that both Maldanoplaca and the subfamily Euclymeninae are

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

Classification

The complete classification of bamboo worms accounts for 6 subfamilies, 38 genera and around 261 species. *Subfamily

Rhodininae Rhodininae is a subfamily of marine polychaete worms in the family Maldanidae. Description Rhodininae worms are characterized by a lack of cephalic and pygidial plates, the presence of posteriorly directed collars in the posterior chaetigerous ...

**'' Rhodine'' – 7 species **'' Boguea'' – 2 species **'' Boguella'' – 1 species *Subfamily

Lumbriclymeninae Lumbriclymeninae is a subfamily of marine polychaete worms in the family Maldanidae. Description Rhodininae worms are characterized by a lack of cephalic and pygidial plates, a keel formed by the prostomium, short and curved nuchal groves, a var ...

**'' Lumbriclymene'' – 10 species **'' Lumbriclymenella'' – 2 species **'' Clymenopsis'' – 4 species **'' Praxillura'' – 6 species *Subfamily

Notoproctinae ''Notoproctus'' is a genus of marine polychaete worms in the family Maldanidae. It is the only member of the subfamily Notoproctinae. Description ''Notoproctus'' worms are characterized by the presence of cephalic and pygidial plates, a cephalic ...

**''

Notoproctus ''Notoproctus'' is a genus of marine polychaete worms in the family Maldanidae. It is the only member of the subfamily Notoproctinae. Description ''Notoproctus'' worms are characterized by the presence of cephalic and pygidial plates, a cephali ...

'' – 9 species *Subfamily Maldaninae **'' Asychis'' (=''Maldanopsis'' ; ''Branchioasychis'' ) – 5 species **'' Bathyasychis'' – 1 species **''

Chirimia Chirimía (sometimes chirisuya in Peru) is a Spanish term for a type of woodwind instrument similar to an oboe. The chirimía is a member of the shawm family of double-reed instruments, introduced to North, Central and South America in the sixtee ...

'' (=''Chrysothemis'' ) – c. 5 species **'' Maldane'' (=''Heteromaldane'' ; ''Sonatsa'' ) – 18 species **'' Metasychis'' – 4 species **''

Sabaco Neferkare Shabaka, or Shabako (Egyptian: 𓆷𓃞𓂓 ''šꜣ bꜣ kꜣ'', Assyrian: ''Sha-ba-ku-u'') was the third Kushite pharaoh of the Twenty-fifth Dynasty of Egypt, who reigned from 705 to 690 BC.F. Payraudeau, Retour sur la succession Sh ...

'' (=''Maldanopsis'' ; =''Branchioasychis'' ) – 9 species *Subfamily Euclymeninae * **'' Aclymene'' – 1 species **'' Axiothella'' (=''Axiotheia'' ) – 19 species **'' Clymenella'' (=''Paraxiothea'' ) – 19 species **'' Clymenura'' – 9 species **'' Euclymene'' (=''Arwidssonia'' ; ''Caecisirrus'' ; ''Leiocephalus'' ) – c. 30 species **'' Eupraxillella'' – 1 species **'' Gravierella'' – 1 species **'' Heteroclymene'' – 2 species **'' Isocirrus'' – 7 species **'' Johnstonia'' – c. 5 species **'' Leiochone'' – 6 species **'' Macroclymene'' – c. 5 species **'' Macroclymenella'' – 1 species **'' Maldanella'' (=''Abyssoclymene'' ) – 12 species **'' Microclymene'' – 5 species **'' Minusculisquama'' – 1 species **'' Mylitta'' – 1 species **'' Petaloclymene'' – 2 species **'' Praxilletta'' (=''Iphianissa'' ; ''Praxilla'' ) – c. 15 species **'' Pseudoclymene'' – 1 species **'' Proclymene'' – 1 species *Subfamily Nicomachinae **'' Micromaldane'' – 7 species **'' Nicomache'' (=''Sabella'' ; ''Clymene'' ) – 17 species **'' Petalopoctus'' – c. 10 species

References

{{Taxonbar, from=Q5106917 Polychaetes Annelid families