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
Colonial or The Colonial may refer to:
* Colonial, of, relating to, or characteristic of a colony or colony (biology)
Architecture
* American colonial architecture
* French Colonial
* Spanish Colonial architecture
Automobiles
* Colonial (1920 au ...
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 ...
Cheilostomatida
Cheilostomatida, also called Cheilostomata, is an order of Bryozoa in the class Gymnolaemata.
They are exclusively marine, colonial invertebrate animals. Cheilostome colonies are composed of calcium carbonate and grow on a variety of surfaces ...
. It is native to the northeastern and northwestern Atlantic Ocean and is also present in Australia and New Zealand.
Description
Colonies of ''Electra pilosa'' form broad mats or star-shaped patches on the surface of the fronds of large algae such as ''
Laminaria
''Laminaria'' is a genus of brown seaweed in the order Laminariales (kelp), comprising 31 species native to the north Atlantic and northern Pacific Oceans. This economically important genus is characterized by long, leathery laminae and relati ...
'' and ''
Fucus serratus
''Fucus serratus'' is a seaweed of the north Atlantic Ocean, known as toothed wrack or serrated wrack.
Description and reproduction
''Fucus serratus'' is a robust alga, olive-brown in colour and similar to '' Fucus vesiculosus'' and ''Fucus spi ...
''. The
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 zoo ...
s also grows in small patches or tufts on the surface of shells and stones, and encircling the fronds of red algae such as ''
Mastocarpus stellatus
''Mastocarpus stellatus,'' commonly known as carrageenan moss or false Irish moss, is a species in the Rhodophyceae division, a red algae seaweed division, and the Phyllophoracea family. ''M. stellatus'' is closely related to Irish Moss (''Ch ...
''. The zooids are packed closely together, are cylindrical and about . Each one has a mineralized
exoskeleton
An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
with a transparent, membranous oval window. The calcified protective covering bears about nine spines (four to twelve), the central one being much longer than the others, giving the colony a hairy (Latin ''pilosa'') appearance.
Distribution
''Electra pilosa'' is native to the northeastern and the northwestern Atlantic Ocean, the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...
, the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
White Sea
The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
and the
Barents Sea
The Barents Sea ( , also ; no, Barentshavet, ; russian: Баренцево море, Barentsevo More) is a marginal sea of the Arctic Ocean, located off the northern coasts of Norway and Russia and divided between Norwegian and Russian territo ...
. It is also present in Australia and New Zealand where it is regarded as an introduced species. It is found from the intertidal zone of sheltered rocky shores down to depths of about .
Biology
A colony starts when a larva settles on a suitable surface and undergoes metamorphosis into an ancestrula. This forms daughter zooids by budding and the colony grows by asexual reproduction. In common with other bryozoans, ''Electra pilosa'' filter feeds with the aid of a crown of
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 ma ...
s 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.flagellates, phytoplankton,
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
, small pieces of algal debris and algal spores. The spines on the exoskeleton, especially the long one, offer protection to the zooid when it is feeding and may grow longer in colonies facing competition from other bryozoans. The growth rate of the zooids varies with the water flow, the temperature, the food supply and the competition from other bryozoan colonies.
The colony is hermaphrodite but individual zooids are either male or female. In Britain, breeding takes place in August and September. The males liberate sperm into the water and the females may actively collect this. Fertilisation takes place in the coelomic cavity of the female into which up to thirty
oocyte
An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The femal ...
s are released. The fertilised embryos are liberated into the sea where they have a long period of
plankton
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...
ic development before settling on a suitable surface. They are present in the water column all year round, but settle between April and November, with settlement peaks in May/June and July/August. The larvae probably use olfactory clues when choosing places to settle and are able to evaluate the suitability of the surface and the proximity of other colonies. A colony can probably survive for several years on a suitable substrate, but will likely last for a shorter period when on an ephemeral base.