Balanus amphitrite
Encyclopedia
Balanus amphitrite is a species
of acorn barnacle
in the Balanidae
family. Its common names include the striped barnacle, the purple acorn barnacle and Amphitrite's rock barnacle. It is found in warm and temperate waters worldwide.
barnacle with distinctive narrow vertical purple or brown stripes. The surface of the test has vertical ribbing. It has a diamond-shaped operculum
protected by a movable lid formed from two triangular plates. It grows to about twenty millimetres in diameter.
or southwestern Pacific Ocean
as fossils of the species have been found in these regions. It has now spread to most of the warm and temperate seas of the world.
roots. It is also found on artificial surfaces such as the hulls of ships, pilings and seawalls. It can be very abundant, with over three hundred individual barnacles being recorded on a single oyster (Crassostrea virginica).
for studies of fundamental and applied larval settlement. This is due to its invasive
behaviour, its worldwide distribution and the ease with which it can be bred in the laboratory. Its genome
has been sequenced.
B. amphitrite is a hermaphrodite
and individuals have both male and female reproductive organs. Sperm is introduced into the mantle cavities of adjacent barnacles through an elongated penis and the fertilised eggs are brooded within the mantle cavity for several months. Free-swimming larvae called nauplii are then released into the water column where they become part of the zooplankton
. In temperate areas, spawning is mainly in the spring and summer but in warmer waters it may continue throughout the year. Individuals can release up to ten thousand eggs per brood and there may be many broods per year. After several moults the last larval stage, the cyprid larva, settles and crawls around looking for a suitable place to cement itself. It does this with a matrix of proteins secreted by the antennae
.
For feeding, B. amphitrite has specialized paired appendages called cirri. These are used to sieve food particles from the water and transfer them to the mouth. They are oriented perpendicular to the general flow direction of the water and the rates of movement vary with the availability of food so as to maximize particle intake.
B. amphitrite can tolerate low salinity levels in estuaries but appears to need higher levels in order to breed. It can also tolerate temperatures as low as 12°C but needs temperatures of at least 15°C to breed which limits its northerly spread.
community. The larvae settle out on and colonise the hulls of ships, harbour structures, buoy
s and the inflow pipes of desalination plants. These become covered with barnacles and other associated hard fouling species. Metal structures become corroded and maintenance costs are increased. The fouling also causes friction between the water and the hulls of ships and this reduces efficiency and increases fuel costs.
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
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...
in the Balanidae
Balanidae
Balanidae is a family of barnacles of the order Sessilia.- Genera :* †Alessandriella Carriol, 2001* Amphibalanus Pitombo, 2004* Arossia Newman, 1982* Austromegabalanus Newman, 1979* Balanus Da Costa, 1778* †Concavus Newman, 1982...
family. Its common names include the striped barnacle, the purple acorn barnacle and Amphitrite's rock barnacle. It is found in warm and temperate waters worldwide.
Description
B. amphitrite is a medium-sized, cone-shaped 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 with distinctive narrow vertical purple or brown stripes. The surface of the test has vertical ribbing. It has a diamond-shaped operculum
Operculum
Operculum may refer to:*Operculum , a stiff structure resembling a lid or a small door that opens and closes**Operculum , a lid on the shell of some gastropods**Operculum , a lid on the orifice of some bryozoans...
protected by a movable lid formed from two triangular plates. It grows to about twenty millimetres in diameter.
Distribution
It is uncertain where B. amphitrite originated but it may have been in the Indian OceanIndian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
or southwestern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
as fossils of the species have been found in these regions. It has now spread to most of the warm and temperate seas of the world.
Habitat
B. amphitrite is a common coastal and estuarine organism found on hard natural surfaces such as bedrock, boulders, mollusc shells and red mangroveRhizophora mangle
Rhizophora mangle, known as the red mangrove, is distributed in estuarine ecosystems throughout the tropics. Its viviparous "seeds," in actuality called propagules, become fully mature plants before dropping off the parent tree...
roots. It is also found on artificial surfaces such as the hulls of ships, pilings and seawalls. It can be very abundant, with over three hundred individual barnacles being recorded on a single oyster (Crassostrea virginica).
Biology
B. amphitrite is a model organismModel organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...
for studies of fundamental and applied larval settlement. This is due to its invasive
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
behaviour, its worldwide distribution and the ease with which it can be bred in the laboratory. Its genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
has been sequenced.
B. amphitrite is a hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
and individuals have both male and female reproductive organs. Sperm is introduced into the mantle cavities of adjacent barnacles through an elongated penis and the fertilised eggs are brooded within the mantle cavity for several months. Free-swimming larvae called nauplii are then released into the water column where they become part of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
. In temperate areas, spawning is mainly in the spring and summer but in warmer waters it may continue throughout the year. Individuals can release up to ten thousand eggs per brood and there may be many broods per year. After several moults the last larval stage, the cyprid larva, settles and crawls around looking for a suitable place to cement itself. It does this with a matrix of proteins secreted by the antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
.
For feeding, B. amphitrite has specialized paired appendages called cirri. These are used to sieve food particles from the water and transfer them to the mouth. They are oriented perpendicular to the general flow direction of the water and the rates of movement vary with the availability of food so as to maximize particle intake.
B. amphitrite can tolerate low salinity levels in estuaries but appears to need higher levels in order to breed. It can also tolerate temperatures as low as 12°C but needs temperatures of at least 15°C to breed which limits its northerly spread.
Fouling
B. amphitrite is part of the biofoulingBiofouling
Biofouling or biological fouling is the undesirable accumulation of microorganisms, plants, algae, or animals on wetted structures.-Impact:...
community. The larvae settle out on and colonise the hulls of ships, harbour structures, buoy
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...
s and the inflow pipes of desalination plants. These become covered with barnacles and other associated hard fouling species. Metal structures become corroded and maintenance costs are increased. The fouling also causes friction between the water and the hulls of ships and this reduces efficiency and increases fuel costs.