Eating and travelling by jet - a little about the life of the salp Thalia democratica скачать в хорошем качестве

Eating and travelling by jet - a little about the life of the salp Thalia democratica

Eating and traveling by jet A little about the life of the salp Thalia democratica (Chordata, Tunicata, Thaliacea, Salpida, Salpidae) By Alvaro E. Migotto Salps are planktonic, gelatinous tunicates that swim actively by jet propulsion. Pumping water through its body, a salp produces a jet of water that drives it forwards, also creating a feeding and respiratory current. The propulsive jet is created by rhythmic contraction of the circular muscular bands that encircles the barrel-shaped, gelatinous and transparent body. The water enters by the oral or inhalant siphon, flows through the spacious pharyngeal cavity, and is expelled by the atrial or exhalant siphon. Circular muscles (sphincters) around oral siphon and a valve at the atrial siphon maintain the flow in one direction. Reverse flow is possible as well. A feeding net is secreted by the endostyle (a ventral U-shaped tube), forming a large sac between endostyle and gill bar that fills most of the pharyngeal cavity. The feeding net is made by very fine filaments arranged in a regular rectangular mesh. In Thalia democratica filament thickness is 30-40 nanometers (0.03 – 0.04 micrometers) and mesh width is approximately 1 micrometer. So the filter or net itself is not visible in low power light microscopy, but its shape is evident when it collects a lot of particles, as for instance by feeding a salp with a dense algal suspension. The sac carrying collected particles (e.g. phytoplankton) is slowly rolled up as it enters the esophagus. New filaments are constantly produced renewing the filter. The salp life cycle involves the alternation of two generations: an aggregated sexual generation (blastozooids) and a solitary asexual generation (oozoid). Solitaries oozoids produce asexually a chain of genetically identical individuals (blastozooids or buds); blastozooids are born female and are fertilized just after release from the oozoid. Once they release one embryo (an oozoid), blastozooids develop testes and fertilize the next generation of newly released buds. So, the embryo is the beginning of the next oozoid generation. Recorded at the Center for Marine Biology (CEBIMar), University of São Paulo (http://www.usp.br/cbm/), at São Sebastião, using a stereomicroscope and a compound microscope with interference-contrast optics. Music: Drifiting by Adrianna Krikl (http://freemusicarchive.org/music/Adr...) See also: Henschke N. 2014. Demography and interannual variability of salp swarms. (Thalia democratica). Mar Biol. 161:149–163. Sutherland KR & Madin LP. 2010. Comparative jet wake structure and swimming performance of salps. The Journal of Experimental Biology 213, 2967-2975. doi:10.1242/jeb.041962. Vargas CA & Madin LP. 2014. Zooplankton feeding ecology: clearance and ingestion rates of the salps Thalia democratica,Cyclosalpa affinis and Salpa cylindrica on naturally occurring particles in the Mid-Atlantic Bight. J. Plankton Res. 26(7): 827-833. doi:10.1093/plankt/fbh068. http://planktonchronicles.org/en/epis... http://video.mit.edu/watch/energy-eff... http://www.imas.utas.edu.au/__data/as... More images of marine organisms at the Marine Biology Image Database – Cifonauta: http://cifonauta.cebimar.usp.br/.