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  • Delving into the world of poisons. Learn how New Zealand’s most poisonous creature was discovered through the investigative work of scientists. Discover what toxins are, how they are identified and how they enter the food web.

    This resource provides explanations of the key concepts encountered when investigating toxins – the ‘basics’ that every student should understand.


    Toxins are poisons. Some scientists define toxins more specifically as poisonous substances that are produced within living cells or organisms (also known as biotoxins).


    Substances that, when introduced into or absorbed by a living organism, causes death, injury or impairment. A poisonous organism only delivers its poison when eaten, touched or inhaled.


    A species that is venomous injects its toxin via biting or stinging. Note that the difference between a poisonous and venomous species is the method of delivery of the toxic substance.


    Anything made of matter is a chemical. They can be in any form, for example, liquid, solid or gas.


    All matter is made up of atoms. A molecule is a group of two or more atoms bonded together.


    A chemical compound is a pure substance made up of two or more distinct elements chemically combined. Water is made by combining the elements hydrogen (H) and oxygen (O) to become H2O.


    A combination of two or more substances in which each substance retains its identity – that is, they can be separated out.


    The amount of a substance that comes into contact with a living organism or some part of a living organism.

    Lethal dose 50 (LD50)

    Lethal dose 50 can also be written as LD50. This is the dose required to kill half the members of a specific animal population. It is used to indicate toxicity.

    Mouse bioassay

    A technique for determining the power of a drug or toxin by measuring its effects on mice.

    Liquid chromatography-mass spectrometry (LC-MS)

    A technique that can be used to detect and give the amount of specific chemicals in a substance.


    Various toxins affect organisms differently. Neurotoxins attack the nervous system. Tetrodotoxin is a neurotoxin.

    Pleurobranchaea maculata

    The scientific name for the grey side-gilled sea slug. Some of these contain the deadly toxin tetrodotoxin.

    Food webs

    The feeding connections among organisms – producers, consumers and decomposers.


    Bioaccumulation refers to the accumulation of substances such as toxins or other organic chemicals in an organism.

      Published 29 October 2015, Updated 7 January 2020 Referencing Hub articles
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