Ostracods: The ultimate survivors

Abstract

Ostracods are tiny crustacean arthropods just a few millimetres long, with a bivalved carapace made of calcium carbonate that covers the whole body, and into which the animal can retreat from the world outside. Because of their diminutive size they are largely overlooked as fossils, but they have a fascinating history. Silent witnesses to life in the seas since the time of trilobites, they have a fossil record extending back to the Early Ordovician, and possibly the Cambrian. Ostracods have survived nearly 500 million years of Earth history including the 'big five' mass extinctions of the Phanerozoic Eon; they are true survivors. They are almost perfectly adapted for the aquatic environments in which they live, and can be found from the ocean abyssal plains to damp leaf litter. The ostracod carapace is a triumph of biological engineering that has been re-configured into myriad different morphologies according to environment. Streamlined and agile species plough through the ocean water column, sometimes reaching a 'giant' size of a centimetre in length, whilst their tinier sea bottom cousins make elaborately ornamented carapaces to withstand the pressures of living at the seabed, or shape their carapaces into forms that facilitate burrowing into sediment. Ostracods are key components of aquatic ecosystems. As primary consumers they are food for larger animals both in seabed and planktonic habitats, and they recycle much of the organic detritus produced by larger animals and plants. Delve into the history of ostracods and it is possible to find pioneers who triumphed in the plankton, early colonisers of terrestrial aquatic ecosystems, and ostracods that literally conquered the land. And in more recent times, ostracods have even hitched rides on rockets into space.

Extremophile at a Glance: Ostracod Crustacean From a Chemoautotrophic Sulphidic Cave Ecosystem

“…SCE species are examples of extremophiles dwelling in habitats subjected to high environmental pressure due to water toxicity. Non-marine ostracods reported from sulphidic groundwaters are very rare, although non-marine ostracods generally thrive in a large array of extreme habitats, such as hot springs (with temperatures exceeding 50°C), cold (up to freezing temperature), acidic (with pH as low as 3.4), and hypersaline waters (at salinities in excess of 100‰) as well as in temporary ponds prone to frequent complete drying or in deep groundwaters [55][56][57][58][59] .…”

First discovery of Eocene coastal-estuarine ostracods from Japan, with the geological history of the migration of estuarine genera in the Far East

“…Generally, many ostracods have strong tolerances of environmental change (Williams et al . 2015), and estuarine environments receive much organic matter from the land (e.g. Irizuki, Matsubara & Matsumoto, 2005).…”

The influence of gravity and light on locomotion and orientation of Heterocypris incongruens and Notodromas monacha (Crustacea, Ostracoda)

“…They inhabit eu- and even hypertrophic waters 12 , 13 and are able to tolerate organic and chemical waste (e.g., water-borne ammonia and phosphate, 14 ) high temperatures, salinity, and pH ranges. 15 Moreover, they can deploy conservation strategies, such as a temporary closure of their valves to overcome momentary prevailing detrimental conditions or the production of dormant eggs to cope with long-lasting unfavorable environmental conditions. 16 , 17 Since these eggs have the ability to hatch in microgravity (µ g ), 18 a BLSS could be restarted at any point, for example after collapse.…”