The depths of our planet’s oceans have long provided a home to many a quirky critter. A particularly curious one is the odd shrimp, Anomalocaris, who struck fear in the hearts of its invertebrate contemporaries as it roamed the seas of the early Cambrian, some 530 million years ago. The story of how this monster got its (not particularly apt) name has been told before, but my blog’s title might be in need of some explanation, so a partial retelling seems appropriate.

The name was coined in 1892 by the Canadian palaeontologist J. F. Whiteaves, who described a rather peculiar fossil that looked a bit like the rear end of a shrimp, albeit a somewhat strange one (see figure 1). He therefore named it Anomalocaris – odd shrimp. A very appropriate name indeed.

Figure 1
Figure 1 – Two Anomalocaris specimens. [Smithsonian Institute]
In 1911, another Canadian palaeontologist, Charles Walcott, described two more fossils from the same geological formation. The first he called Peytoia, a round, banded structure that looks not unlike a pineapple slice (see figure 2). Walcott believed Peytoia to be a jellyfish, though it was unclear why it had a hole in the middle.

Figure 2
Figure 2 – A Peytoia specimen. [Walcott 1911, Smithsonian Miscellaneous Collections 57]
Yet another fossil was interpreted by Walcott as a squashed sea cucumber, which he called Laggania (see figure 3). Thus, we have three organisms: Anomalocaris, half a shrimp, Peytoia, a jellyfish, and Laggania, a sea cucumber. Various palaeontologists have tried to take away some of the confusion surrounding these three organisms, especially when more specimens of each of them were found. Several candidate heads for Anomalocaris have been proposed; Peytoia‘s status as a jellyfish has been questioned; and Laggania was reinterpreted as a sponge. However, it took several decades for these puzzles to be satisfactorily solved.

Figure 3
Figure 3 – A Laggania specimen. [Walcott 1911, Smithsonian Miscellaneous Collections 57]
Finally, in 1985, Harry Whittington and Derek Briggs published their account of these fossils. By dissecting several specimens, they found that Laggania was actually a large, predatory animal, and that Peytoia was its mouth – not a jellyfish at all. Moreover, it had two Anomalocaris feeding appendages in front of its mouth. These three fossils thus turned out to be part of a single creature. However, the rules of name-giving in biology are such that the first name is always to be preferred, and this rather intimidating animal is therefore forever called Anomalocaris – odd shrimp (see figure 4).

Figure 4
Figure 4 – Artist’s impression of Anomalocaris prominently displaying its pineapple-mouth and shrimpy feeding appendages. [Copyright: John Sibbick]
The late American palaeontologist Stephen Jay Gould called the history of Anomalocaris ‘a tale of humor, error, struggle, frustration, and more error, culminating in an extraordinary resolution …, the largest and fiercest of Cambrian organisms.’¹ Thus I proudly name my blog after this odd shrimp, for it perfectly embodies what I am after: sea-creatures of all walks of life, with interesting stories to tell.


  1. Gould, S. J. 1989. Wonderful Life. The Burgess Shale and the Nature of History. Vintage, page 194.

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