Marine invertebrates: extant examples

Reconstructions of invertebrates are often a minor aspect because they require too much precision. Also, many exoskeletons adequately reflect the external shape. What may be true of many crustaceans or sea urchins unjustifiably obscures the great variety of soft tissues. This is proven by neontological examples: the pteriomorph clam Lima; the octopod Argonauta; the lingulate brachiopod Lingula.

The isolated Argonauta arm shell or eggcase (background) is produced exclusively by females and is used for reproduction, partly for locomotion. There are other examples of tools directly secreted from animals’ bodies, such as spider webs, cocoons, mucus webs of hagfish, beeswax, or swiftlet’s nests. However, these are stationary, or temporarily bound to situations. Similarly, feathers torn out by force are used as nesting material, for example by eider ducks. It remains that the argonaut’s shell is presumably the only mobile and durable object that it secreted and used by the same animal.

digital painting, 2024

academic education, Tech.Univ. Bergakademie Freiberg

see fossil Nautilida and fossil rhynchonelliform brachiopods