Chthamalus stellatus
Encyclopedia
Chthamalus stellatus, common name
Poli's stellate barnacle, is a species
of acorn barnacle common on rocky shores in South West England
, Ireland
, and Southern Europe
. It is named after Giuseppe Saverio Poli
.
barnacle
that attaches to rocks and other firm materials in the intertidal zone
using its membranous
base. It is basically cone-shaped but can assume a more tubular shape in a crowded colony. Like other sessile barnacles, as an adult C. stellatus is a suspension feeder that stays in its fixed shell and uses its feathery, rhythmically beating appendages – actually modified legs – to draw plankton
and detritus
into its shell for consumption.
The chalky white shell of C. stellatus has a kite-shaped opercular opening
when it is a juvenile and an oval operculum opening when it is an adult. The shell is made up of six solid wall plates of approximately equal size. Its relatively narrow rostral plates remain separate from its rostrolateral plates and do not fuse. C. stellatus has bright blue tissue
with black and orange markings which can be seen when its opercular aperture is not tightly closed. Depending upon environmental conditions and the amount of food available, it can reach up to 14 millimetre (0.551181102362205 in) in diameter.
es are significantly longer than their bodies and are used by the stationary "functional males" to search the area for an equally stationary "functional female" neighbour to fertilise.
Barnacles of this species produce about 1,000 to 4,000 eggs per brood when functioning as female. The fertilised eggs remain inside the shell of the adult until they are released as nauplii, free swimming larva
e which float on currents along with other plankton
. After several moults
they metamorphose
into a cyprid, a stage at which they cannot feed. The cyprid swims in search of a suitable surface on which to attach itself, head first, in order to metamorphose into the familiar, hard-shelled, immobile form. The duration of its breeding season can be temperature dependent, and it produces fewer brood
s near the northern limit of its range.
. It especially favours islands and headlands as opposed to bays and more protected areas. It is a southern, warm-water species but has been discovered as far north as Shetland and as far east as the Isle of Wight
.
The vertical distribution of C. stellatus overlaps with Chthamalus montagui
(considered the same species as C. stellatus until 1976) and Semibalanus balanoides
with the specific prevalence of one species over another in a given locale possibly related to differences in the distribution of the species' larval stages
.
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
Poli's stellate barnacle, is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of acorn barnacle common on rocky shores in South West England
South West England
South West England is one of the regions of England defined by the Government of the United Kingdom for statistical and other purposes. It is the largest such region in area, covering and comprising Bristol, Gloucestershire, Somerset, Dorset, Wiltshire, Devon, Cornwall and the Isles of Scilly. ...
, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, and Southern Europe
Southern Europe
The term Southern Europe, at its most general definition, is used to mean "all countries in the south of Europe". However, the concept, at different times, has had different meanings, providing additional political, linguistic and cultural context to the definition in addition to the typical...
. It is named after Giuseppe Saverio Poli
Giuseppe Saverio Poli
Giuseppe Saverio Poli was an Italian physicist, biologist and natural historian.His collections, with those of the Royal Bourbon Museum, were the foundation of the Zoological Museum of Naples...
.
Description
C. stellatus is a sessileSessility (zoology)
In zoology, sessility is a characteristic of animals which are not able to move about. They are usually permanently attached to a solid substrate of some kind, such as a part of a plant or dead tree trunk, a rock, or the hull of a ship in the case of barnacles. Corals lay down their own...
barnacle
Barnacle
A barnacle is a type of arthropod belonging to infraclass 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 erosive settings. They are sessile suspension feeders, and have...
that attaches to rocks and other firm materials in the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
using its membranous
Biological membrane
A biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...
base. It is basically cone-shaped but can assume a more tubular shape in a crowded colony. Like other sessile barnacles, as an adult C. stellatus is a suspension feeder that stays in its fixed shell and uses its feathery, rhythmically beating appendages – actually modified legs – to draw plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
and detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
into its shell for consumption.
The chalky white shell of C. stellatus has a kite-shaped opercular opening
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
when it is a juvenile and an oval operculum opening when it is an adult. The shell is made up of six solid wall plates of approximately equal size. Its relatively narrow rostral plates remain separate from its rostrolateral plates and do not fuse. C. stellatus has bright blue tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
with black and orange markings which can be seen when its opercular aperture is not tightly closed. Depending upon environmental conditions and the amount of food available, it can reach up to 14 millimetre (0.551181102362205 in) in diameter.
Reproduction
Like most barnacles, C. stellatus is hermaphroditic and capable of self-fertilisation when isolated, but individuals typically take on either a male or female role in order to mate. Their penisPenis
The penis is a biological feature of male animals including both vertebrates and invertebrates...
es are significantly longer than their bodies and are used by the stationary "functional males" to search the area for an equally stationary "functional female" neighbour to fertilise.
Barnacles of this species produce about 1,000 to 4,000 eggs per brood when functioning as female. The fertilised eggs remain inside the shell of the adult until they are released as nauplii, free swimming larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e which float on currents along with other plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
. After several moults
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
they metamorphose
Métamorphose
"Métamorphose" - a song by French singer Amanda Lear released in 1989 by Carrere Records.- Song information :"Métamorphose" was the first single from Amanda's French-Italian album Tant qu'il y aura des hommes. The album was actually a re-release of Uomini più uomini, and consisted mostly of down-...
into a cyprid, a stage at which they cannot feed. The cyprid swims in search of a suitable surface on which to attach itself, head first, in order to metamorphose into the familiar, hard-shelled, immobile form. The duration of its breeding season can be temperature dependent, and it produces fewer brood
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...
s near the northern limit of its range.
Habitat and range
C. stellatus attaches to exposed rocky shores in the mid to low eulittoral zone in the northeastern Atlantic OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
. It especially favours islands and headlands as opposed to bays and more protected areas. It is a southern, warm-water species but has been discovered as far north as Shetland and as far east as the Isle of Wight
Isle of Wight
The Isle of Wight is a county and the largest island of England, located in the English Channel, on average about 2–4 miles off the south coast of the county of Hampshire, separated from the mainland by a strait called the Solent...
.
The vertical distribution of C. stellatus overlaps with Chthamalus montagui
Chthamalus montagui
Chthamalus montagui, common name Montagu's stellate barnacle, is a species of acorn barnacle common on rocky shores in South West England, Ireland, and Southern Europe.The vertical distribution of C...
(considered the same species as C. stellatus until 1976) and Semibalanus balanoides
Semibalanus balanoides
Semibalanus balanoides is a common and widespread boreo-arctic species of acorn barnacle. It is common on rocks and other substrates in the intertidal zone of north-western Europe and both coasts of North America.-Description:...
with the specific prevalence of one species over another in a given locale possibly related to differences in the distribution of the species' larval stages
Crustacean larvae
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow...
.