Jersey Post will release 3 stamps and a beautiful MS on 7thApril 2011.Being an island, Jersey’s coastline is rich in marinetreasures to discover and explore and it is now the turn of Squirts and Sponges to be showcased in this, the ninth issue in the Marine Life series. Sea squirts, or tunicates, belong to the invertebrates family of marine animals although some do not have some primitive vertebrae features. They are foud from the intertidal zone to the deepest depths, permanently fixed to a surface. Some live individually, others live in groups or colonies. They have a thick outer coat for protection, called a ‘test’ and derive their name from their habit of drawing water and food through ‘siphons’ before squirting it out again. Sponges, also, known as ‘Porifera’, meaning ‘pore-bearing’, draw the water in through a complex of pores and canals. Both species come in variety of shapes, sizesand colours affording the perfect opportunity for illustration.
Tunicates (Sea squirts), also known as urochordates, are members of the subphylum Tunicata or Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the Phylum Chordata. While most tunicates live on the ocean floor, others – such as salps, doliolids and pyrosomes – live above in the pelagic zone as adults. They were historically known as Ascadia, and are now commonly known as sea squirts and sea pork.
Sponges are animals of the phylum Porifera. Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells. While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells that can transform into other types, often migrating between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, and the shapes of their bodies are adapted to maximize the efficiency of the water flow. All are sessile aquatic animals and, although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 metres (5.5 mi) (Wikipedia source).