With their ability to build calcareous tubes 1.85 to 2 mm in mouth diameter and 20 to 40 mm in length, F. enigmaticus form expansive congregations of large intertwining reef-like aggregates that may exceed 7m in diameter. The tubes are flared at the openings and have collar-like rings along their length. In their early stages they are white in color, but accumulate brown stains as they get older. The tubes are often covered with green algae. They have a crown of 12–20 gray, green, or brown radioles (heavily ciliated feather-like tentacle), pinnulate branchiae (gills) that they force out from the tube opening to filter-feed (Costello et al., 2001; Luppi and Bas, 2002; Shumka et al., 2014).
Ficopomatus enigmaticus colonies are normally found attached to rocks, jetties, boats and any other surface (Davies et al., 1989; Picker and Griffiths, 2011).
No communication strategies have been documented for Ficopomatus enigmaticus.
Ficopomatus enigmaticus is a non-indigenous species whose native distribution is thought to be Australia (Davies et al., 1989; Schwindt and Iribarne, 2000). Furthermore, F. enigmaticus has been reported outside of its native distribution in from Milnerton Lagoon, on the west coast, to Kosi Bay, on the east coast, but is only found at isolated sites along this range. It is also found in the Zandvlei estuary 20km south of Cape Town (McQuaid, 2013).
Ficopomatus enigmaticus occupies lagoons (Milnerton Lagoon, Table Bay to Kosi Bay), Marinas (Zandvlei, False Bay); estuaries (Bruschetti et al., 2008; Davies et al., 1989; McQuaid, 2013; Obenat and Pezzani, 1994). F. enigmaticus colononies occur both in the intertidal zone and on floating docks (Pernet et al., 2016). The morphology of Ficopomatus enigmaticus reefs may vary among environments according to water depth, type of substrate and direction of water flow (Fornós et al., 1997).
F. enigmaticus is a suspension-feeder (Obenat and Pezzani, 1994). Its mode of feeding (filter-feeding) helps reduce turbidity it also negatively affects the benthic plankton and thus works in an opposite way to natural reefs (Obenat and Pezzani, 1994).
SEX and LIFE CYCLES
Sex: F. enigmaticus is gonochoristic, referring to the state of having just one of at least two distinct sexes in any one individual organism (Cohen and Carlton, 1995). It is an annual iteroparous (characterized by multiple reproductive cycles over the course of its lifetime) whose females may produce 1-2 batches of small eggs per lifespan with free spawning ova fate. The eggs develop in planktonic planktothrophic larvae which act as dispersal phase. The larvae settle on hard substrates and grow as sedentary suspension-feeder worms (Obenat and Pezzani, 1994).
*Planktotrophy, meaning “feeding on plankton” refers to development via a larva that must feed in the plankton in order to develop to metamorphosis. Species with planktotrophic development produce many small energy-poor eggs with adequate nutrient reserves for the development of a feeding larva.
Family life: F. enigmaticus creates reef-like aggregates, in which tubes grow vertically to the substrate in clumps and attach to each other (Katsanevakis et al., 2014).
THE BIG PICTURE
Describe the role of this species in the ecosystem and how adapts to its environment: Use the following subheadings
Friends and foes
The reef-like aggregates formed by F. enigmaticus offer substrate, shelter, and food for many species such as fish and migratory birds. Among a few others, Ficopomatus enigmaticus are excellent food for many species, including fish (Katsanevakis et al., 2014).
F. enigmaticus exhibits what is referred to as a soft strategy, where they build their reefs such that they are collapsible. This mechanism is suggested to allow for colonization processes that lead to high density and close packing of the tubes. Newly settled tubes consolidate the remains of the previous aggregate through “self-binding” (Bianchi and Morri, 2001).
Poorer world without me
In the Zandvlei estuary, Ficopomatus enigmaticus plays a fundamental role in the maintenance of water quality by greatly reducing particle loads through its feeding activities (Davies et al., 1989).
People and I
Ficopomatus enigmaticus is a non-indigenous species and poses the following threats to native species, namely: ecosystem engineering; abundance, diversity and distribution of associated organisms; fouling of boat hulls; injure paddlers and swimmers as they are calcareous (Davies et al., 1989; Picker and Griffiths, 2011).
*Any observations of this species can be uploaded on to iSpot in order to feed into the current project to map the distribution of marine alien species in South Africa.