Tunicates Phylum Chordata

Luminescence of Pyrosoma. All species of the genus Pyrosoma (about 10 species) are bioluminescent. Pyrosoma is one of the few organisms reported to luminesce in response to light (Bowlby et al., 1990). The luminescence emission spectrum of Pyrosoma atlantica is bimodal according to Kampa and Boden (1957), with the primary peak near 482 nm, and the secondary near 525 nm. Swift et al. (1977) reported the emission maxima of two Pyrosoma species at 485 and 493 nm, respectively, and Bowlby et al. (1990) found an emission peak at 475 nm with P. atlantica. A corrected bioluminescence spectrum of P. atlantica (A.max 485 nm) reported by Herring (1983) is shown in Fig. 10.5.2. 

The source of light emission. Each individual animal in a colony of Pyrosoma has two groups of luminous cells at the entrance to the branchial sac (Herring, 1978a). The luminous cells contain tubular inclusions whose identity has been a matter of dispute for nearly a century. Buchner (1914) originally suggested that the inclusions were symbiotic luminous bacteria. However, efforts to cultivate luminous bacteria from the luminous cells of Pyrosoma consistently failed. In 

---

Ascidians or tunicates (Phylum Chordata) belong to the class of Ascidiacea and are common marine animals whose body is enclosed in a jacket or tunic. The animals are attached to rocks and are either solitary or colonial. They continuously filter seawater to obtain minute organisms and particulate organics. As was originally discovered by Henze the animals concentrate vanadium from seawater to levels about 10 times that present in seawater (35 nM), a phenomenon that has attracted considerable interest. The transition metal is present... 

Phylum Chordata Tunicates, sharks, bony fishes, amphibians, reptiles, birds, mammals... 

Tunicates or ascidians belong to the phylum Chordata. Ascidiacea is a class of the subphylum Urochordata (Tunicata) and members of this... 

The phylum Chordata, to which we ourselves belong, includes not only the vertebrates but also more primitive marine animals that have a spinal cord. Among these primitive species, which may be related to early ancestral forms, are the tunicates or sea squirts. They have a very high concentration of vanadium in their blood. 

---