(a species of owlet moth (Noctuid)) Some caterpillars, after they emerge from their egg, can increase their weight by 25,000 times.

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Taxonomy

The taxonomy and classification of proto-mantis shrimp is an ongoing project. There are several groups and they form a paraphyletic series leading to the modern mantis shrimp.

Anatomical detail of Daidal acanthocercus

Anatomical detail of Daidal acanthocercus. The top image shows the animal with the front end curved to the right. Both the legs of the pleon (AR) and cephalothorax (Th) are visible. The bottom image shows details of the animal's tailfan, including the protopod of the uropods (P) with its spines (arrows), the outer (Ex) and inner (En) rami of the uropods, and the telson (T). © Contributions to Zoology

Morphology

The segmented body of the spiny-tailed proto-mantis shrimp is divided into 2 regions:

  • an anterior (front) cephalothorax
  • a posterior (rear) pleon

The cephalothorax includes the:

  • head with its eyes and sensory appendages (antennules and antennae)
  • thorax with its battery of 4 pairs of legs (thoracopods) with spiny claws. Because the thorax contains 8 segments, we can conclude that 4 pairs of limbs have not been preserved. 

A carapace or head shield envelops the front part of the cephalothorax. 

The hind region of the body - the pleon - is made up of 6 segments. Only fragments of the limbs of the first 5 pleon segments are known, while the 6th segment has a pair of broad, flap-like appendages called uropods. 

The uropods, consisting of an inner (endopod) and outer (exopod) branch, flank the telson - the hindmost part of the pleon. Together, the telson and uropods form a tailfan.

Characterising proto-mantis shrimp

There are 2 basic types of proto-mantis shrimp, characterised by either:

  1. thoracopods that are subequal in size
  2. 1 pair of significantly enlarged thoracopods, like modern mantis shrimp

The spiny-tailed proto-mantis shrimp is of the first type.

  • The telson of Daidal acanthocercus
    Anatomical details of Daidal acanthocercus

    View a slideshow of images showing anatomical details of this proto-mantis shrimp.

  • Drawing of Bairdops beargulchensis
    Lookalikes

    Find out which species show similarities to Daidal acanthocercus, and how to distinguish them.

  • Example of a modern mantis shrimp, Odontodactylus scyallarus
    Evolution

    Learn how proto-mantis fossils can shed light on the evolution of the body plan of mantis shrimp and their specialised claws.

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Glossary

Paraphyletic
A group of organisms is said to be paraphyletic if it contains a single common ancestor but excludes some of the descendants of this ancestor.