Kingdom Animalia
Phylum Chordata
Subphylum Tunicata
Class Ascidiacea
Colonial ascidians (AKA tunicates or sea squirts)
Our closest invertebrate relatives! After rapid development over the course of just a few days, our sea squirts have metamorphosed and are close to maturation. I've actually become quite fond of these little guys because they have the coolest body plan. They have an oral and an atrial siphon that water enters and exits, respectively, through. The water goes through mucus-covered gills into the atrium. The mucus in the gills slits (more technically called pharyngeal slits) traps little particles from the sea water and carries them to the esophagus for digestion. The pharyngeal slits have cilia around them to transport the mucus.
Although we do not know the species of the ascidians, we do know that they are colonial. What does this mean? There are main types of ascidians: solitary and colonial.
Solitary ascidians live singularly by themselves, or form large, packed groups. When in groups, however, they do not reproduce asexually like most other aggregating organisms.
Although we do not know the species of the ascidians, we do know that they are colonial. What does this mean? There are main types of ascidians: solitary and colonial.
Solitary ascidians live singularly by themselves, or form large, packed groups. When in groups, however, they do not reproduce asexually like most other aggregating organisms.
Colonial ascidians can be divided into social or compound. In social ascidians, individual organisms in the colony have the same body shape as if they were to stand on their own, but they are connected at the base by their stolons. In compound ascidians, individual colony members (zooids), have their own incurrent siphons, but share one common atrial siphon with many other zooids. So cool!
Unfortunately, it is too early in development to determine if these are social or compound ascidians. Can't wait to find out!
Unfortunately, it is too early in development to determine if these are social or compound ascidians. Can't wait to find out!
Below are pictures and videos of adult sea squirts.
Fertilized 4/23/13
Images Captured 5/2/13
Fertilized 4/23/13
Images Captured 5/2/13
Pictures:
In this image you can clearly see the main parts of the body plan: incurrent siphon, excurrent siphon, pharyngeal slits, stomach, intestine.
Video:
Unfortunately, again, due to technical difficulties, the videos would not upload directly onto this web page, so I have attached the links to the YouTube videos. Please read the description to get a better idea of what you are looking at!
Gill Slits:
http://www.youtube.com/watch?v=p0UBJUsorgo
http://www.youtube.com/watch?v=le0K4IwUagU
Heart:
http://www.youtube.com/watch?v=bXD1x0mX0gU
http://www.youtube.com/watch?v=ZeITM0moiHA
-Amy Kim
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