Natural History

Ascidians are most commonly known as Sea Squirts. They belong to the phylum chordata. Yes, I know, by looking at the pictures below you would begin to think I'm crazy. Not just crazy for putting a webpage up regarding sponges, ascidians and bryozoans - they sure aren't cute and cuddly. They are a subclass of chordata called Tunicata, appropriately, because in their larval stage there appear tadpole-like because of a notochord and dorsal nerve. Although their adult form has no distinguished head, their larval form does. The larvae eventually settles into a place and metamorphoses into an attached (to the substrate) adult phase. Despite their unpopularity for touristy beach combers, there is more then 2,500 species known! Ascidians are sessile organisms and generally come in three different forms:

Sea squirts have two main openings (very distinct, when clean). These two openings are the in and out of the digestive tract. Water intakes from one opening and passes through many perforations (atrium cavity) and soaks up any of the microscopic food in the water. The excess water exits through the remaining opening therefore defining the term "squirt". If you own a boat, you are unfortunately familiar with tunicates (Colonial/Compound). These love to attach to firm surfaces such as boats and propellers and cause problems (although, no scientific evidence has show that these tunicates actually obtain the emotion of "love", but the idea is just the same).
Please enjoy the pictures below (scroll over pictures to see where they were found)!



Please visit the Marine Ecology class homepage to see the rest of our animals!



Ascidians seen in class:

    Friday Harbor - Trip on the Centenial Boat, sandy bottom troll - UW FHL
    Aplidiopsis pannosum - (Possibly??) Pale Mushroom Compound Tunicate
    Friday Harbor - Trip on the Centenial Boat, sandy bottom troll - UW FHL
    Unidentifiable Sea Squirt that was thrown back to sea!
    Friday Harbor - Argyle Creek, gravel stream bed
    Cnemidocarpa finmarkiensis - Shiny Red Tunicate (On a Japanese Oyster)
    Tongue Point - near Salt Creek, outer coast, rocky intertidal
    Unidentifiable Compound Tunicate
    Tongue Point - near Salt Creek, outer coast, rocky intertidal
    Unidentifiable Compound Tunicate that settled inside a shell




Ascidians not seen in class but still worth mentioning!:


    Pyura haustor - Warty Tunicate (taken from: http://home.uchicago.edu/)

    Boltenia villosa - Hairy Tunicate (taken from: http://convoluta.ucdavis.edu/research/2006/12/sea_squirt_sunday_boltenia_vil.html)

    Metandrocarpa taylori - Orange Social Tunicate (taken from: http://convoluta.ucdavis.edu/gallery/)

    Cystodytes lobatus - Loabed Compound Tunicate (taken from: http://www.metridium.com/monterey/other/other.html)

    Aplidium solidum - Red Ascidian, on the left(taken from: http://www.racerocks.com/)

    Botryllus schlosseri - Harbor Star Ascidian (taken from: http://www.marinbi.com/ascidiacea/)