Beautiful & Creepy Things about Tunicates! Echinoblog Off Topic!

Image by Leander Wiseman

Today, a little off topic time for some tunicate love!

For those who are not familiar, tunicates are actually members of the same overall group to which humans and all other vertebrates belong! A subgrouping, called the Tunicata within the larger phylum Chordata. Honestly, the relationship is pretty basic info which you can find with a quick Google search

Most times, tunicates are small, out of the way or encrusting (i.e., covering surfaces over a wide area) but can be very abundant, carpeting areas until nothing else grows there..such as this one (Botrylloides diegensis) which is an invasive in San Francisco Bay from Asia.

 Image by Luis A Solórzano, KQUEST

Under many conditions, tunicates are ugly and kind of bland colored things that are common components of fouling communities. Its species such as this one which earn the oh so lovely common name "sea pork"(Amaroucium californicum). And so, they get a bad rap. 

image by Jkirkhart35

But tunicates are often gorgeous and attractive animals. PLUS, they do weird and unusual (if kinda creepy) things! Let's go see! 

1. Some Basics
This shows two siphons: one is where water goes IN and the other is where it goes OUT.

Image by Arne Kuilman, from Anilao, Philippines

Food gets caught in the "Pharyngeal basket" (=the "filter" for its filter feeding) where it gets moved down to the stomach. A pretty simple overall anatomy. But note, it has well-developed organs that you would find in a proper animal.  This is important later...

From the Marine Life Information Network

This gives you a general idea of the animal as a whole (not sure if this is the exact same species but you get the general notion)

Image by Prilfish

 Basket Close ups! 

Image by Steve de Neef

Cross section! the space between the 'tunic" and the feeding basket

Image by "stupidhead"

Image by Star Tsai

INSIDE the basket!

Image by Eric Cheng

Image by Christian Loader

Image by Steve de Neef

2. Some Diversity... 
Some tunicates are individuals

Image by bybegone

Whereas other forms are colonial...

Image by Patrick Nilsson

Botrylloides magnicoecum from Australia. And yes, those are apparently the REAL colors.

Image by Leander Wiseman

Botrylloides leachi from Australia

Image by John Tumbull

Fantastic image by Pat Sinclair

Other tunicates are more....unusual in appearance (I think these are solitary)  BEHOLD! Sea Tulips! Pyura spinifera from Australia!

Here's only a few...

Here's a LOT of them

Image by Richard Ling

Another stalked tunicate, Oxycorynia fascicularis from Anilao in the Philippines

Image by Optical Allusion

Stalked GREEN tunicates! Same species? Oxycorynia fascicularis

Image by Mer Mate-Eunice Koo

And although I've been focusing on shallow water, I can't get past tunicates without the obligatory showing of the famous DEEP-SEA predatory tunicate (Megalodicopia hians) !! The IN siphon is modified into a mouth and the OUT siphon kicks out the tunicate poop!   Let's let the British narrator take us away!


3. The predatory tunicate is a great segue for the vice versa! People EAT tunicates. As I've outlined here.  Its called the "sea pineapple" among other things in Asian cultures, but different species (called 'sea violets') are eaten by Europeans..

Image by sjbutterfield2

MMmm........tunicates and kimchi....

Image by Mark Deibert Photography

4. Tunicates are a little creepy 
If tunicates have similar enough tissues (historecognition) ie. are similar enough two physically different individuals can physically FUSE together.

Why say it, when you can SHOW it?

the description from the video:

This video shows a fusion event in progress between compatible individuals of the sea squirt, Botryllus schlosseri. At the beginning, terminal parts of vasculature, called ampullae, which surround the colony, have come into contact (one colony is on the top right, the other on the bottom left, out of the field of view). The ampullae push into each other repeatedly, and finally the cell layers between two ampullae fuse, and results in both individuals sharing a common circulation. 
Fusion can best be seen on the top left, but occurs in several places in the region of interaction. The decision to fuse or reject is based on whether the two colonies 'match' each other, analogous to how humans accept or reject transplants.

See this essay for more.  But bear in mind, tunicates may look simple like sponges-but they aren't! 

Sponges don't have tissue, so those videos where they grind em' up and they get back together?

Not that hard for animals that are still essentially just colonies of cells. Proper ANIMALS with tissues don't typically do stuff like that.  The fusion shown in tunicates above?  That's like you and your family, suddenly fusing into one big amorphous pile. Squicky, eh?

Go here to learn more about this.

5. Where can I learn MORE about tunicates?
*Did you know that tunicates accumulate the metal Vanadium in their body tissues? go here to learn more.
*The Dutch ascidian Site! 
*The Tunicate Web Portal! 
*Will tunicates be used as biofuel? 
and my colleague Jarrett Byrnes writes a blog that often involves tunicates!