Obese Ascidian – Phallusia obesa

, Obese Ascidian - Phallusia obesa, Phallusia obesa
Depth: 6 - 15 m

Afghanistan, Alaska, Algeria, Andaman and Nicobar, Angola, Antarctica, Antigua and Barbuda, Arctic, Argentina, Ascension Island, Australia, Austria, Azerbaijan, Azores Islands, Bangladesh, Belarus, Bolivia, Bosnia and Herzegovina, Brazil, Brunei Darussalam, Bulgaria, Cambodia, Cameroon, Canada, Canary Islands, Cayman Islands, Central African Republic, Chile, China, Cocos Islands, Comoros, Congo, Cook Islands, Corsica Island, Crete Island, Croatia, Curaçao, Cyprus, Czech Republic, Democratic Republic of the Congo, Denmark, El Salvador, England, Equatorial Guinea, Falkland Islands, Faroe Islands, Finland, France, French Polynesia, Gabon, Galapagos Islands, Germany, Ghana, Gibraltar, Greece, Greenland, Guinea, Guinea-Bissau, Hawaii, Honduras, Hungary, India, Indonesia, Iran, Iraq, Ireland, Italy, Ivory Coast, Japan, Kazakhstan, Kyrgyzstan, Laos, Macedonia, Madagascar, Madeira Islands, Malawi, Malaysia, Marshall Islands, Mauritius, Mexico, Micronesia, Moldova, Morocco, Mozambique, Myanmar, Namibia, New Zealand, Nicaragua, Nigeria, Norfolk Island, North Korea, Northern Ireland, Norway, Oman, Pakistan, Palestine, Papua New Guinea, Peru, Philippines, Poland, Portugal, Reunion Island, Romania, Russia, Saint Martin, São Tomé and Príncipe, Sardinia Island, Scotland, Senegal, Serbia, Sicily Island, Sierra Leone, Singapore, Slovakia, Slovenia, Solomon Islands, Somalia, South Africa, South Georgia And The South Sandwich Islands, South Korea, Spain, Sweden, Taiwan, Tajikistan, Tanzania, Tonga, Tunisia, Turkey, Turkmenistan, Turks and Caicos Islands, Ukraine, United Kingdom, United States Minor Outlying Islands, Uruguay, US Minor Islands, USA, Uzbekistan, Vatican City, Venezuela, Vietnam, Virgin Islands, Wales, Yemen, Zambia, Zimbabwe

Amvrakikos Gulf, Andaman Sea, Arabian Sea, Aral Sea, Arctic Ocean, Atlantic Ocean, Baltic Sea, Barents Sea, Bay of Bengal, Bay of Biscay, Beaufort Sea, Bering Sea, Black Sea, Bohai Sea, Cantabrian Sea, Celtic Sea, Chukchi Sea, Coral Sea, Dead Sea, English Channel, German Bight, Great Barrier Reef, Greenland Sea, Gulf of Aden, Gulf of Fonseca, Gulf of Maine, Gulf of Mexico, Gulf of Saint Lawrence, Halmahera Sea, Iberian Sea, Indian Ocean, Java Sea, Korinthiakos Gulf, Labrador Sea, Levantine Sea, Lingayan Gulf, Mediterranean Sea, Moro Gulf, Okhotsk Sea, Pacific Ocean, Pagassitikos Gulf, Salish Sea, Saronikos Gulf, Scotia Sea, Sea of Azov, Sea of Marmara, Siberian Sea, South China Sea, Southern Ocean, Thermaikos Gulf, Yellow Sea

The Obese Ascidian, scientifically known as Phallusia obesa, is a fascinating marine invertebrate belonging to the tunicate family. Its unique characteristics and distribution make it an intriguing subject of study in marine biology.

Description & Characteristics

Phallusia obesa, true to its name, is a relatively large ascidian, reaching a maximum size of about 10 centimeters in length. Its body is typically oval-shaped, with two siphons located at one end: an incurrent siphon for drawing in water and an excurrent siphon for expelling filtered water. The outer tunic, which gives ascidians their common name of “sea squirts,” is usually rough and leathery in texture, providing protection and structural support.

Habitat and Occurrence

The Obese Ascidian, Phallusia obesa, is a common sight in various coastal regions, particularly in the Mediterranean Sea and the North Atlantic Ocean. It typically inhabits rocky substrates and seagrass beds, often found attached to hard surfaces in intertidal zones and shallow subtidal areas. This species thrives in the infralittoral zone, which encompasses the region from low tide to the depth where light starts to dim significantly.

Taxonomy

Phallusia obesa is classified within the phylum Chordata, a group that includes all vertebrates. This species belongs to the Class: Ascidiacea, which encompasses all sea squirts. It is further classified within the Order: Phlebobranchia, a group characterized by simple gill slits and a single row of tentacles surrounding the incurrent siphon. Finally, Phallusia obesa belongs to the Family: Ascidiidae, a diverse family of solitary ascidians.

Feeding

Phallusia obesa is a filter feeder, relying on plankton as its primary food source. Water is drawn into the incurrent siphon, passing through a complex system of gill slits where tiny food particles are trapped. The filtered water is then expelled through the excurrent siphon. This efficient feeding mechanism allows Phallusia obesa to thrive in environments rich in plankton, playing a crucial role in the marine food web.

Associated Species

Image References

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