Friday, January 18, 2013

Creature Feature: Tunicates

Beautiful! See the two siphons in each tunicate?
Tunicate-encrusted mooring line

Look at the brilliant color of these tunicates above – beautiful! They look like pretty marine flowers, no? No! Tunicates are chordates, related to vertebrates (animals with spinal chords); these little critters have a primitive version of a spine in the larval stage, when they’re free-living and tadpole-like, though it disappears by the time they settle onto a substrate, attach and develop into their sedentary adult form. Tunicates feed by pulling food particles out of the water that enters their barrel-like bodies through the inflow siphon, and discharged filtered water and waste through the outflow siphon. Though they resemble anatomically simple animals such as anemones, they actually are quite more complex. Tunicates are hermaphrodites, producing both eggs and sperm. The sperm is released into the water to be taken in by other tunicates to fertilize their eggs, and the eggs remain within the adult until they hatch. The larvae are released for dispersal. Tunicates come in a wide variety of forms and colors, as seen here. As you can seen here, in addition to attaching to the bottom, tunicates also quite willingly attach to lines underwater, such as those on mooring balls.

Tunicate Fun Fact: Tunicates are also called “sea squirts” because, when you take them out of the water, they squirt. Always a good trick to play on an unaware bystander.

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