Geologic time scaleThe geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history.
PyrenoidPyrenoids are sub-cellular micro-compartments found in chloroplasts of many algae, and in a single group of land plants, the hornworts. Pyrenoids are associated with the operation of a carbon-concentrating mechanism (CCM). Their main function is to act as centres of carbon dioxide (CO2) fixation, by generating and maintaining a CO2 rich environment around the photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Pyrenoids therefore seem to have a role analogous to that of carboxysomes in cyanobacteria.
Coral bleachingCoral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae (dinoflagellates that are commonly referred to as algae) that live inside their tissue, causing the coral to turn white. The zooxanthellae are photosynthetic, and as the water temperature rises, they begin to produce reactive oxygen species. This is toxic to the coral, so the coral expels the zooxanthellae.
ExoskeletonAn exoskeleton (from Greek έξω éxō "outer" and σκελετός skeletós "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. Some large exoskeletons are known as "shells". Examples of exoskeletons within animals include the arthropod exoskeleton shared by chelicerates, myriapods, crustaceans, and insects, as well as the shell of certain sponges and the mollusc shell shared by snails, clams, tusk shells, chitons, and nautilus.
Lunar geologic timescaleThe lunar geological timescale (or selenological timescale) divides the history of Earth's Moon into five generally recognized periods: the Copernican, Eratosthenian, Imbrian (Late and Early epochs), Nectarian, and Pre-Nectarian. The boundaries of this time scale are related to large impact events that have modified the lunar surface, changes in crater formation through time, and the size-frequency distribution of craters superposed on geological units.
Marine protistsMarine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as marine single-celled prokaryotes (bacteria and archaea) and later evolved into more complex eukaryotes. Eukaryotes are the more developed life forms known as plants, animals, fungi and protists. Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly single-celled and microscopic.
SymbiodiniumSymbiodinium is a genus of dinoflagellates that encompasses the largest and most prevalent group of endosymbiotic dinoflagellates known. These unicellular microalgae commonly reside in the endoderm of tropical cnidarians such as corals, sea anemones, and jellyfish, where the products of their photosynthetic processing are exchanged in the host for inorganic molecules. They are also harbored by various species of demosponges, flatworms, mollusks such as the giant clams, foraminifera (soritids), and some ciliates.
Algae scrubberAn algae scrubber is a water filtering device (not to be confused with a scrubber pad used to clean glass) which uses light to grow algae; in this process, undesirable chemicals are removed from the water. Algae scrubbers allow saltwater, freshwater and pond hobbyists to operate their tanks using natural filtration in the form of primary production, much like oceans and lakes. An algae scrubber filters water by moving water rapidly over a rough, highly illuminated surface, which causes algae to start growing in large amounts.
DinocystDinocysts or dinoflagellate cysts are typically 15 to 100 μm in diameter and produced by around 15–20% of living dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic-walled dinocysts are often resistant and made out of dinosporin. There are also calcareous dinoflagellate cysts and siliceous dinoflagellate cysts. The first person to recognize fossil dinoflagellates was Christian Gottfried Ehrenberg, who reported his discovery in a paper presented to the Berlin Academy of Sciences in July 1836.
TyrannosauridaeTyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three. All of these animals lived near the end of the Cretaceous Period and their fossils have been found only in North America and Asia.
