Lightbulb sea squirts
Clavelina lepadiformis is a colonial blob of jelly with a difference. Unlike most squirts, it is easily identified. A transparent tube is topped with a white circle and lines that run from the base to the rim, this looks like the filament of a tungsten bulb. They are short-lived lasting between 1 and 2 years and have an interesting life strategy. In the winter they die back and growth then comes from buds at the base. These are in fact either sexually produced offspring or clones asexually budded from the parent zooid or reabsorbed adults reduced to buds. These start to grow in spring and by May are full size, a huge 2cm high.
Lightbulbs actively pump water and are filter feeders, the active pumping means they can live in areas of less water flow, so hunt under rocks and in crevices. The colony is attached at the base and so forms a clump, the individual units (zooids) each reproduce only once, eggs being fertilised internally then give rise to free-swimming larvae, these settle within a few days and grow into adults depending on the time of year, they might not grow until the next spring. Interestingly some studies have found that light bulbs in very sheltered harbours do not all die back over winter in warmer waters, this might become a trend here with warming.
Few organisms attach to the squirts this might be because they are very flimsy and offer little adhesion or it could be because they contain toxic elements (cytotoxic alkaloid). They are eaten by flatworms and others though. These are great things to find and very photogenic but I always imagine them lighting up at night and creating a party atmosphere in those dark crevices.
References http://www.marlin.ac.uk/species/detail/1483
Lightbulbs actively pump water and are filter feeders, the active pumping means they can live in areas of less water flow, so hunt under rocks and in crevices. The colony is attached at the base and so forms a clump, the individual units (zooids) each reproduce only once, eggs being fertilised internally then give rise to free-swimming larvae, these settle within a few days and grow into adults depending on the time of year, they might not grow until the next spring. Interestingly some studies have found that light bulbs in very sheltered harbours do not all die back over winter in warmer waters, this might become a trend here with warming.
Few organisms attach to the squirts this might be because they are very flimsy and offer little adhesion or it could be because they contain toxic elements (cytotoxic alkaloid). They are eaten by flatworms and others though. These are great things to find and very photogenic but I always imagine them lighting up at night and creating a party atmosphere in those dark crevices.
References http://www.marlin.ac.uk/species/detail/1483