Siphonophore, or 3-D Model? - Observation of the Week, 10/25/22

Our Observation of the Week is this Bassia bassensis siphonophore, seen off of New Zealand by @luca_dt!

As a child, Luca Davenport-Thomas tells me “I would always love rock pooling or flipping rocks on the beach to find amazing things but it is only recently, about the same time as I signed up to iNaturalist, that I really started looking. 

When I started doing nature photography with my compact camera (Olympus TG-6) I began to take pictures of the tiniest and most amazing things…

I will usually snorkel in a marine reserve which hosts some extraordinary biodiversity, not far from where I live in Wellington. When I snorkel I am often searching for nudibranchs, and anything else interesting I find along the way is a bonus.

On a recent snorkeling outing north of Wellington, Luca came across the creature you see above.

Although Nudibranchs are my favourite things to search for, I admit that the most amazing snorkels I have are when there is a plankton bloom. From time to time we get amazing salp blooms filled with siphonophores, jellyfish and other incredible alien-like creatures. And sometimes a member of these blooms are the Bassia bassensis siphonophores. They are possibly the most unbelievable siphonophore to see. With their strange symmetrical, geometric shape and vivid white edges, they look like a digital 3D model come to reality. Swimming through them and all the other plankton feels like being on another world.

Siphonophores are actually colonial organisms, composed of smaller zooid organisms that are specialized for certain functions like predation, locomotion, reproduction, etc. Bassia bassensis feeds mostly on copepods by using its stinging tentacles, and reaches a length of 6-8 centimeters. Perhaps the most well known siphonophore is the Portuguese man o' war (Physalia physalis), and another siphonophore, the giant siphonophore (Praya dubia), can grow up to 40 m (130 ft).

Luca (above) is currently working toward a master’s degree in marine biology and studies Lepas Gooseneck barnacles, but he also hopes to one day participate in some deep sea exploration. He joined iNat last May, mostly for nudibranch ID help, 

but I quickly realised that a lot of the things I was observing were hardly or not at all observed before. This sparked my passion to keep exploring and learning along the way. Quickly, I became a part of a great community who share similar interests. Using iNaturalist I have become way more knowledgeable of marine life taxonomy. It is quite amazing to think how little I knew before, and how only in the short time I’ve used iNaturalist, it has completely opened my mind.

(Photo of Luca by Nadine McGrath)

- Here’s a good intro video to siphonophores and other colonial marine organisms.

- Check out the most-faved siphonophore observations on iNat!

- This Bassia bassensis is bizarre for sure, but is it as bizarre as the “chiton crab” seen in New Zealand back in 2014 by @emily_r?

Posted on October 25, 2022 07:17 PM by tiwane