tunicary

[Lat. tunica a tunic; English suff.- ary.] Zool.: Any individual of the Tunic at a (q. v.). tu-ni-ca-ta, s. pl. [Neut. pl. of Lat. tunic at us, pa. par. of tunico =to clothe with a tunic (q. v.).] Zoology : Sea-squirts; a group of animals now usually made a sub-kingdom, with one cla , Ascidioida, containing three sub-orders, or families, of which Ascidia, Salpa, and Pyrosoma are the types. They are all marine, and are protected by a leathery elastic integument, or tunic, which takes the place of a shell. None attain a length of more than a few inches, and some are minute and almost microscopic. They have no distinct head, and no separate organs of prehension or locomotion. They po e an alimentary canal suspended within the integument; the mouth opens into a large chamber which usually occupies the greater part of the cavity of the mantle, and which is known as the respiratory sac, or branchial sac, its walls are perforated by numerous apertures. This sac opens into the cœsophagus, which is followed by the stomach and intestine coiled upon itself, and terminating in the cloaca, which opens near to the mouth. The heart consists of a simple contractile tube, open at both ends. The nervous system consists of a single ganglion, situated at one side of the mouth. All the Tunic at a are free during the earlier portion of their existence; at a later period most are fixed; some are simple, while others present various degrees of combination; and, with few exceptions, the sexes are combined in a single individual. They form a connecting link between the Vertebrata and the Invertebrata, from the fact that many of them in the larval state are furnished with a notochord, which atrophies in the adult. Ray Lankester ( Degeneration , p. 41) considers them "degenerate vertebrata, standing in the same relation to fishes, frogs and men, as do the barnacles to shrimps, crabs, and lobsters."