''Amathia verticillata'', commonly known as the spaghetti bryozoan, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of colonial

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

ns with a bush-like structure. It is found in shallow temperate and warm waters in the western Atlantic Ocean and the Caribbean Sea and has spread worldwide as a fouling organism. It is regarded as an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

in some countries.

Description

Colonies of ''Amathia verticillata'' resemble miniature trees up to a metre (yard) wide and consist of a dense mass of feeding

zooid A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooi ...

s known as autozooids connected to each other by slender branching

stolon In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...

s in diameter. The stolons are attached to the substrate by an adhesive disc and are translucent and may be brownish or bluish. The autozooids are in two rows along the stolons, each zooid being sac-like and in length. The mouth of each autozooid bears a retractable crown-like feeding structure known as a

lophophore The lophophore () is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Hyolitha, and Phoronida, which collectively constitute the protostome group Lophophorata.tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s. The stolon has a jointed appearance and is composed of a series of tubular non-feeding heterozooids. All the zooids within the colony are connected via pores in their walls and coelomic fluid can be transferred along the stolon and between adjacent autozooids.

Distribution and habitat

Colonies of ''Amathia verticillata'' are found in shallow water in the tropical and subtropical western Atlantic and the Caribbean Sea and many other parts of the world. It is tolerant of a range of water conditions but grows best at salinities of at least 30ppt and water temperatures over . It is a common species in the

Indian River Lagoon The Indian River Lagoon is a grouping of three lagoons: the Mosquito Lagoon, the Banana River, and the Indian River, on the Atlantic Coast of Florida; one of the most biodiverse estuaries in the Northern Hemisphere and is home to more than 4,300 ...

where it grows vigorously from April to September but dies back during winter. ''Amathia verticillata'' is a fouling organism and its typical habitat is growing on the blades of

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

es, the

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

of large

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

s, the roots of mangroves, rocky

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

s, the shells of

bivalve molluscs Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

, piers, breakwaters and other man-made structures, the hulls of boats, floating masses of seaweed and other floating debris.

Biology

Each autozooid feeds by expanding its lophophore, the extended tentacles of which filter phytoplankton from the water. It has been estimated that each zooid can process 8.8 ml of water in a day, and the zooids on a square metre of

seagrass meadow A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...

can filter some 184,728 litres (48,613 gallons) of water a day. By this means, this bryozoan can play a useful role in improving water quality. Expansion of the colony is by

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is know ...

and new colonies can also be formed by

fragmentation Fragmentation or fragmented may refer to: Computers * Fragmentation (computing), a phenomenon of computer storage * File system fragmentation, the tendency of a file system to lay out the contents of files non-continuously * Fragmented distributi ...

. It has been shown that one end of a cut piece of stolon will develop attachment structures to anchor it to the substrate within about twenty-four hours. This bryozoan is a hermaphrodite and reproduction also takes place sexually. The larva is planktonic, settles on a hard surface and develops into a heterozooid which attaches itself to the substrate with an adhesive disc.

Ecology

''Amathia verticillata'' sometimes grows in association with the honeysuckle tunicate (''Perophora viridis''), the stolons of which intertwine with those of the bryozoan. The colonies provide hiding places for juvenile fish and for the amphipods,

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

polychaete worms 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 m ...

and the other small

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s on which the young fish feed. The tissues of ''Amathia verticillata'' contain certain secondary metabolites that render it unappetizing to many potential

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

. The main one is a bromo-

alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...

which has been shown to prevent settlement of

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...

and

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

larvae on the colony. One of the few creatures that does feed on it is the nudibranch '' Okenia zoobotryon'' which is thought to live, feed and lay its eggs almost exclusively on the bryozoan and whose tissues may then contain many of the same anti-predator chemicals.

Invasive species

There are concerns about ''Amathia verticillata'' as an invasive species. It can develop into huge aggregations and cause fouling of fishing gear, block sea-water inlets, out-compete native species and upset food chains by filtering phytoplankton from the water.

References

{{Taxonbar, from1=Q49632830, from2=Q4168309 Ctenostomatida Animals described in 1822 Taxa named by Stefano delle Chiaje