Arthropods: Hard Cases!

Glossary of Key Terms

• Arthropods:
  The largest and most diverse group of animals on Earth, characterised by a hard exoskeleton, segmented body, and jointed legs. Their name means "jointed feet."

• Chitin:
  A tough, fibrous substance that forms the hard exoskeleton of arthropods.

• Crustaceans:
  A major group of arthropods, typically aquatic (e.g., crabs, lobsters), but includes terrestrial forms like woodlice. They often have more than eight legs and two pairs of antennae.

• Detritivores:
  Organisms that feed on decaying organic matter, such as dead plant material. Millipedes are an example.

• Diptera:
  The order of insects commonly known as true flies, characterised by having only two functional wings, with hindwings reduced to halteres.

• Ecological Engineers:
  Organisms that physically modify, create, or maintain habitats, thereby influencing the availability of resources to other species. Bivalve molluscs are an example.

• Exoskeleton:
  A hard, external skeleton that supports and protects an animal's body, characteristic of arthropods.

• Halteres:
  Small, club-shaped structures that are the reduced hindwings of Diptera, functioning as gyroscopes for flight stability.

• Hemiptera:
  The order of insects commonly known as true bugs, characterised by piercing and sucking mouthparts. Includes suborders like Heteroptera (true bugs), Sternorrhyncha (aphids), and Auchenorrhyncha (cicadas).

• Hymenoptera:
  A diverse order of insects including bees, wasps, ants, and sawflies, many of which are known for their social behaviour and roles as pollinators or predators.

• Incomplete Metamorphosis:
  A type of insect development where the life cycle consists of three stages: egg, nymph, and adult, with nymphs resembling miniature adults. Seen in Hemiptera and Orthoptera.

• Insect Galls:
  Abnormal growths or swellings on plants caused by gall-inducing insects manipulating plant tissues through chemical signals, providing shelter and nutrients for larvae.

• Invertebrates:
  Animals without a backbone or spinal column. Arthropods and Molluscs are examples.

• Lepidoptera:
  The order of insects comprising butterflies and moths, known for their scaled wings and often vibrant colours.

• Mollusca:
  A diverse phylum of invertebrates with soft bodies, often protected by a hard shell. Includes snails, clams, octopuses, and nudibranchs.

• Myriapods:
  A group of arthropods known for their many legs and long, segmented bodies, including centipedes and millipedes.

• Nymph:
  An immature form of an insect that undergoes incomplete metamorphosis, resembling a smaller version of the adult without fully developed wings or reproductive organs.

• Odonata:
  An ancient order of aerial predatory insects encompassing dragonflies and damselflies, known for their large compound eyes and voracious appetites.

• Orthoptera:
  An order of insects renowned for their melodic calls and acrobatic leaps, including crickets, grasshoppers, katydids, and locusts.

• Phylum:
  A major taxonomic rank below Kingdom and above Class, used to classify organisms based on shared fundamental body plans.

• Pollination:
  The transfer of pollen from the anther to the stigma of a plant, essential for plant reproduction, often carried out by insects like bees.

• Segmented Body:
  A body plan composed of repeated units or segments, a key characteristic of arthropods.

• Stridulation:
  The process by which some insects, particularly Orthoptera, produce sound by rubbing specialised body parts together.

• Terrestrial Crustaceans:
  Crustaceans that have adapted to life on land, such as woodlice.

• Venation:
  The pattern of veins in the wings of insects, often intricate and unique to different species or orders.