Invasion History

First Non-native North American Tidal Record:
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Microcosmus exasperatus was described by Heller from the West Indies or northern South America in 1876 (Van Name 1921; Van Name 1945). However, it is widely distributed in the tropical Atlantic and Indo-Pacific and is cryptogenic over this range. It is considered introduced in the Mediterranean (Amor et al. 2016; Turon et al. 2007; Ramos-Espla et al. 2013), Northwest Africa (Monniot and Monniot 1994), Pacific Islands (Guam, Lambert 2002; Lambert 2003, Hawaii, Monniot 1981; the Galapagos (Lambert 2019). In 2009, it was collected at the Pacific entrance to the Panama Canal (Carman et al. 2011).

North American Invasion History:

Invasion History on the West Coast:

Invasion History on the East Coast:

Invasion History on the Gulf Coast:

Invasion History in Hawaii:

Invasion History Elsewhere in the World:

Microcosmus exasperatus is considered cryptogenic in the eastern and western tropical Atlantic, and in the Indo -West Pacific but is introduced in the central and eastern Mediterranean, and Pacific oceanic islands. The invasion of M. exasperates was complicated by the invasion of its Indo-Pacific congener, M. squamiger, which has invaded much of the western Mediterranean (Shenkar and Loya 2009; Ramos and Espla 2013). The earliest record of M. exasperates was on the Western Djerba Island. Tunisia, in the Gulf of Gabes in 1998. Later records were on the coast of Israel (2002), and Beirut, Lebanon (2004), and Alsancak Harbour, Turkey, on the Aegean Sea (2004) (Shenkar and Loya 2009; Ramos and Espla 2013). Microcosmus exasperatus is considered a likely Lessepsian species, which probably colonized the Mediterranean through the Suez Canal (Shenkar and Loya 2009; Ramos and Espla 2013).


Description

Microcosmus exasperatus is a solitary tunicate, but usually occurs in dense clumps or aggregates. The body is ovate, but irregular, attached by a large area on the posterior ventral side. The test is rough, and leathery. Apertures are usually located on short, wart-like siphons about a third of the body length and are directed away from each other. However, sometimes the oral siphon is terminal with a long straight siphon, while the atrial siphon is short and about half-way along the body. Large specimens reach about 55 mm. The color vaires from reddish-brown to purple, with pink or bright-orange siphons (Van Name 1945; Kott 1985; Goodbody and Webber 2003).

This species is frequently confused with the very similar species Microcosmus squamiger (Mastrototaro and Dappiano 2005; Turon et al. 2007). One of the few characteristics used to distinguish between the two species is the shape of the internal siphonal spines. The spines of M. squamiger are very short, about 15-25 µm long, and shaped like fingernails with serrated rims, while M. exasperatus has longer pointed spines, about 40-50 µm long, which are posteriorly hooked (Kott, 1985; Mastrototaro and Dappiano 2005).


Taxonomy

Taxonomic Tree

Kingdom:   Animalia
Phylum:   Chordata
Subphylum:   Tunicata
Class:   Ascidiacea
Order:   Stolidobranchia
Family:   Pyuridae
Genus:   Microcosmus
Species:   exasperatus

Synonyms

Microcosmus biconvolutus (Sluiter, 1898)
Microcosmus distans (Heller, 1878)
Microcosmus haemisphaerium (Sluiter, 1904)
Microcosmus miniatus (Verrill, 1900)
Microcosmus variegatus (Heller, 1878)
Microscosmus claudicans var. australis (Hartmeyer and Michaelsen, 1928)
Ascidia cavernosa (Leseur, 1823)
Ascidia variabilis (Leseur, 1823)
Microcosmus anchylodeirus (Traustedt, 1883)
Pyura cavernosa (Hartmeyer, 1911)
Pyura variabilis (Hartmeyer, 1911)

Potentially Misidentified Species

Microcosmus squamiger
Microcosmus squamiger is native to the Indo-Pacific, but is widely introduced, in the Western Mediterranean, Azores, South Africa, and California and Mexico.

Ecology

General:

Life History- A solitary tunicate is ovoid, elongate or vase-like in shape, with two openings or siphons. Most solitary tunicates attach to substrates by their side or base, but some attach with a conspicuous stalk. They are sessile filter feeders with two siphons, an oral and an atrial siphon. Water is pumped in through the oral siphon, where phytoplankton and detritus is filtered by the gills, and passed on mucus strings to the stomach and intestines. Waste is then expelled in the outgoing atrial water.

Solitary ascidians are hermaphroditic, meaning that both eggs and sperm are released to the atrial chamber. Eggs may be self-fertilized or fertilized by sperm from nearby animals, but many species have a partial block to self-fertilization. Depending on the species, eggs may be externally or internally fertilized. In external fertilizers, eggs and sperm are released through the atrial siphon into the surrounding water column were fertilization takes place. In internal fertilizers, eggs are brooded and fertilized within the atrial chamber and then released into the water column upon hatching. Fertilized eggs hatch into a tadpole larva with a muscular tail, notochord, eyespots, and a set of adhesive papillae. The lecithotrophic (non-feeding, yolk-dependent) larva swims briefly before settlement. Swimming periods are usually less than a day and some larvae settle immediately after release, but the larval period can be longer at lower temperatures. Once settled, the tail is absorbed, the gill basket expands, and the tunicate begins to feed by filtering (Barnes 1983).

Microcosmus exasperatus is widespread in subtropical and tropical marine waters at polyhaline to euhaline salinities (Van Name 1945; Nagar and Shenkar 2016). It has been found on a wide range of substrates on pilings, stones, mangrove roots, and coral reefs, buoys, floats, and vessel hulls (Van Name 1945; Woods Hole Oceanographic Institution 1952; Godwin 2002).

Food:

Phytoplankton

Trophic Status:

Suspension Feeder

SusFed

Habitats

General HabitatMarinas & DocksNone
General HabitatCoral reefNone
General HabitatMangrovesNone
General HabitatRockyNone
General HabitatVessel HullNone
General HabitatOyster ReefNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone
Vertical HabitatLittoralNone

Life History


Tolerances and Life History Parameters

Minimum Temperature (ºC)12Experimental (Nagar and Shenkar 2016)
Maximum Temperature (ºC)30Experimental (Nagar and Shenkar 2016)
Minimum Salinity (‰)24Field (Brazil, Marins et al. 2010); 33 PSU (Experimental, Israel, Nagar and Shenkar 2016)
Maximum Salinity (‰)45Experimental (Nagar and Shenkar 2016)
Minimum Length (mm)55Van Name 1945
Broad Temperature RangeNoneWarm temperate-Tropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Impacts are unknown.


Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
SP-XXI None 1940 Def Estab
CAR-II None 1878 Crypto Estab
CAR-VII Cape Hatteras to Mid-East Florida 1885 Crypto Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 1884 Crypto Estab
NA-ET4 Bermuda 1900 Crypto Estab
SA-II None 1925 Crypto Estab
WA-IV None 1955 Crypto Estab
WA-V None 1955 Crypto Estab
EA-V None 0 Crypto Estab
EA-III None 1908 Crypto Estab
RS-1 None 1918 Crypto Estab
RS-2 None 1918 Crypto Estab
RS-3 None 1918 Crypto Estab
NWP-2 None 0 Crypto Estab
EAS-III None 0 Crypto Estab
EAS-I None 0 Crypto Estab
SP-IV None 0 Crypto Estab
SP-XII None 1949 Def Estab
SP-V None 0 Crypto Estab
MED-IV None 1998 Def Estab
CAR-IV None 1878 Crypto Estab
CAR-III None 1884 Crypto Estab
AUS-I None 0 Crypto Estab
AUS-II None 0 Crypto Estab
AUS-VIII None 0 Crypto Estab
AUS-III None 0 Crypto Estab
AUS-XII None 0 Crypto Estab
AUS-X None 1853 Crypto Estab
WA-I None 1963 Crypto Estab
SA-III None 2005 Crypto Estab
WA-II None 1965 Crypto Estab
MED-V None 2007 Def Estab
G040 Rookery Bay 1884 Crypto Estab
S206 _CDA_S206 (Vero Beach) 1884 Crypto Estab
CAR-II None 1884 Crypto Estab
CAR-III None 1884 Def Estab
S050 Cape Fear River 1885 Crypto Estab
SP-XI None 1951 Def Estab
NWP-3a None 0 Crypto Estab
G060 Sarasota Bay 1952 Crypto Estab
G045 _CDA_G045 (Big Cypress Swamp) 1983 Crypto Estab
G010 Florida Bay 1982 Crypto Estab
AUS-IV None 0 Crypto Estab
SEP-H None 2008 Def Estab
CIO-II None 2004 Crypto Estab
CIO-I None 2004 Crypto Estab
SA-IV None 0 Crypto Estab
SP-VII None 0 Crypto Estab
S190 Indian River 0 Crypto Estab
PAN_PAC Panama Pacific Coast 2009 Def Estab
PAN_CAR Panama Caribbean Coast 0 Crypto Estab
SEP-Z None 2016 Def Unk
MED-VI None 2004 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude

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