科学用語集

Biological Taxonomy

A system that organises living organisms into nested ranks: kingdom → phylum → order → family → genus → species

Kingdom

The highest rank in biological taxonomy — marine life belongs to several kingdoms including animals, plants, fungi, and bacteria

Phylum (plural: Phyla)

The second rank in taxonomy — e.g. Chordata (fishes and mammals) and Echinodermata (echinoderms)

Genus

A group of closely related species — the first part of the scientific name. Example: Carcharhinus (grey reef sharks)

Species

The smallest taxonomic unit — organisms that interbreed and produce fertile offspring. The second part of the scientific name

Binomial Nomenclature

Linnaeus’s two-part naming system: genus + species in italics. Example: Chelonia mydas (green sea turtle)

Endemic Species

A species found only in one geographic area. About 12% of Red Sea species are endemic

Ecosystem

A community of living organisms plus their physical and chemical environment, interacting as one unit

Food Chain

The sequence of energy transfer from algae (producers) to herbivores to predators to decomposers

Food Web

A more realistic map of feeding links — interlocking food chains in an ecosystem

Apex Predator

An organism at the top of the food chain that is not preyed on as a healthy adult. Examples: great white shark and giant squid

Symbiosis

A close relationship between two species — mutualism (both benefit), parasitism (one benefits), or commensalism (neutral)

Mutualism

A symbiotic relationship in which both partners benefit — e.g. cleaner wrasses and large fishes, or clownfish and anemones

Parasitism

A symbiotic relationship in which the parasite benefits and the host is harmed — intestinal worms in fishes are a common example

Biotope

A habitat with uniform physical and chemical conditions — e.g. a seagrass biotope or a reef-slope biotope

Biodiversity

The variety of living species in an area — measured by species number, distribution, and genetic variation

Invasive Species

A species introduced outside its native range that harms local species — e.g. Caulerpa taxifolia in the Mediterranean

Coral Polyp

The basic animal unit of a coral — a small anemone-like organism that builds an external limestone skeleton

Zooxanthellae

Microscopic symbiotic algae (Symbiodinium) living in coral tissue and supplying about 90% of its food via photosynthesis

Coral Bleaching

Expulsion of zooxanthellae when coral is stressed (heat or pollution), turning it white — the coral does not die immediately but is at risk

Calcification

The polyp’s construction of its limestone skeleton (CaCO₃) — affected by temperature, ocean acidification, and light

Hard Coral (Scleractinia)

Corals that build hard limestone skeletons — the foundation of coral reefs

Soft Coral (Alcyonacea)

Corals that lack a hard limestone skeleton and feel flexible — including gorgonians and nephtheids

Parthenogenesis

Reproduction by a female without fertilisation — documented in zebra sharks and some other marine species

Thermocline

A water layer where temperature changes sharply with depth — a barrier between surface and deep water

Halocline

A layer where salinity changes sharply — seen as a visual shimmer when diving in caves

Oceanography

The science of the oceans — physical, chemical, biological, and geological properties

Tidal Cycle

Regular rise and fall of sea level due to the Moon and Sun — it affects dive planning and coastal navigation

Ocean Currents

Persistent ocean water movement driven by wind, heat, salinity, and Earth’s rotation. They distribute heat and nutrients globally

Ocean pH

A measure of seawater acidity — typically 8.1–8.3 (alkaline). Extra CO₂ uptake lowers pH (acidification) and dissolves coral skeletons

Thermohaline Circulation

The global conveyor of ocean water — a slow circulation that takes about 1,000 years per loop and carries oxygen to the deep

Upwelling

Cold, nutrient-rich water rising from the deep — it creates rich fishing grounds and fuels biological production

Photosynthesis

Conversion of sunlight, carbon dioxide, and water into organic matter and oxygen. Algae produce 50–80% of Earth’s oxygen

Chemosynthesis

Energy production from chemical reactions instead of light — used by organisms at deep-sea hydrothermal vents

Bioluminescence

The ability to produce chemical light — about 90% of twilight-zone animals have it. Used for communication, hunting, and camouflage

Plankton

Microscopic drifters — phytoplankton produce food; zooplankton eat it

Phytoplankton

Microscopic plant-like plankton that photosynthesise — the main source of ocean oxygen and the base of the marine food web

Ampullae of Lorenzini

Shark sense organs that detect weak electric fields from prey — they allow hunting in darkness and sediment

Lateral Line

A fish sensory system that detects pressure changes and vibration — it senses nearby movement without sight

Bioaccumulation

Build-up of toxins (such as mercury and plastics) in tissues — concentration rises up the food chain

Adaptation

A heritable trait that improves survival in a given environment — e.g. gelatinous bodies of deep-sea fishes under huge pressure

International Union for Conservation of Nature

The International Union for Conservation of Nature — it publishes the Red List assessing global threat status

Convention on International Trade in Endangered Species

An international treaty that regulates and bans trade in threatened species — covering sharks, turtles, mantas, and others

Marine Protected Area (MPA)

A legally designated sea area that protects the ecosystem and regulates human activity — from full bans to partial limits

Sustainable Fishing

Fishing that stays within species’ reproductive rates — including quotas, minimum sizes, and closed areas

Ocean Acidification

A drop in seawater pH from excess CO₂ uptake — it dissolves coral and shell skeletons and affects larval growth

Blue Carbon

Carbon stored in coastal marine systems (seagrass, mangrove, saltmarsh) — often more efficient than tropical forests

Dive Theory

The physical and physiological principles of diving: Boyle’s law, Henry’s law, decompression sickness, and dive-table calculations

Decompression Sickness (DCS)

Occurs on a rapid ascent when nitrogen bubbles form in tissues and blood — it requires an immediate recompression chamber

Thermocline (Diving)

A sudden temperature change while diving that causes a visual shimmer — typically seen between 15–30 m in the Red Sea

Dive Site

A defined underwater location with reefs, fishes, or wrecks — recorded with GPS and a depth profile

Coral Garden

A dense, diverse coral area that forms an exceptional visual scene — often at 5–25 m