Empty shells of Twisted Ark, Trisidos tortuosa (Linnaeus), at Cairns

The angularity of this bivalved shell made it immediately noticeable on the sandy beach at Cairns. It is called a Twisted Ark because of the strange configuration of the shell which is strongly twisted with a sharp ridge from the top to the margin. The Latin name is Trisidos tortuosa (Linnaeus), formerly Arca tortuosa. It varies from 60 – 100 mm in length and occurs on the Australian coast from the Northern Territory to Queensland.

Reference

Jansen, P. (1996) Common Seashells of Coastal Northern Queensland, privately published in Townsville, Australia, November 1996. ISBN 0 646 29824 0. 

Empty shells of Twisted Ark, Trisidos tortuosa (Linnaeus), at Cairns

Empty shells of Twisted Ark, Trisidos tortuosa (Linnaeus), at Cairns

Empty shells of Twisted Ark, Trisidos tortuosa (Linnaeus), at Cairns

4 Replies to “Seashells at Cairns 3”

  1. Yes, it is rather like an abstract sculptural form. I wonder why it evolved that particular shape and what kind of competitive edge the design would give the species in life?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: