Biodiversity and Classification of Living Organisms: Invertebrates, Vertebrates and Plants

Posted on Oct 10, 2026 in Biology

The diversity of organisms includes microorganisms, plants, and animals.

It exists as a result of the diversity of habitats and climates.

Sources of Food

Animals and plants supply food to humans.

Balance in Nature

Balance is maintained through the cycle of nutrients, pollination, and interaction between organisms.

Recreational Places

Areas that are rich in biodiversity can be developed as recreational places.

Medical Uses

Herbs are widely used in the manufacture of medicines and cosmetics.

Raw Materials for Industries

Timber, bamboo, and rattan are commonly used to make musical instruments, furniture, and to construct buildings.

Education

Scientific research on microorganisms, animals, and plants increases knowledge.

Invertebrates

Invertebrates are animals without a backbone.

Classification

Without Legs

  • Without a segmented body: Sponge, Sea Anemone, Coral, Planarian, and Snail
  • With a segmented body: Tapeworm, Earthworm, and Leech

With Legs

  • Have segmented bodies with a hard outer shell (exoskeleton)
    Three pairs of legs: Ant, Butterfly, Cockroach
    More than three pairs of legs: Spider, Horseshoe Crab, Prawn, Centipede, Scorpion

Vertebrates

Vertebrates are animals with a backbone.

Classification

Fish

  • Skin: Hard, slimy scales
  • Blood: Poikilothermic
  • Breathing: Gills
  • Reproduction: Lay eggs
  • Fertilization: External

Amphibians

  • Skin: Moist skin
  • Blood: Poikilothermic
  • Breathing: Young have gills; adults have lungs and moist skin
  • Reproduction: Lay jelly-like eggs without a shell
  • Fertilization: External

Reptiles

  • Skin: Hard skin and scales
  • Blood: Poikilothermic
  • Breathing: Lungs
  • Reproduction: Lay eggs with a shell
  • Fertilization: Internal

Birds

  • Skin: Feathers; scaly feet and wings
  • Blood: Homeothermic
  • Breathing: Lungs
  • Reproduction: Lay eggs with a hard shell
  • Fertilization: Internal

Mammals

  • Skin: Fur or hair
  • Blood: Homeothermic
  • Breathing: Lungs
  • Reproduction: Give birth and nurse their young
  • Fertilization: Internal

Thermoregulation

Poikilothermic animals (fish, amphibians, reptiles): body temperature changes with the surroundings.

Homeothermic animals (birds, mammals): body temperature does not change with the surroundings.

Non-Flowering Plants

Moss

  • Reproduces by spores
  • Non-vascular

Fern

  • Reproduces by spores
  • Vascular

Conifer

  • Bears cones
  • Vascular

Flowering Plants

Flowering plants produce fruits that contain seeds, each with cotyledons.

Monocotyledons

Examples: Paddy and maize plants

  • One cotyledon
  • Fibrous root
  • Parallel-veined leaves
  • Mostly non-woody stems

Dicotyledons

Examples: Tomato plant and durian tree

  • Two cotyledons
  • Tap root
  • Network-veined leaves
  • Woody stems

Dichotomous Key

A dichotomous key is used to systematically identify and classify organisms based on their similarities and differences.

Couplets consist of two statements describing the characteristics of a particular organism.

Example: Pomfret, chicken, lion, frog, and snake

  1. (A) Poikilothermic: go to 2
    (B) Homeothermic: go to 3
  2. (A) Scaly skin: go to 4
    (B) Non-scaly skin: Frog
  3. (A) Non-feathered: Lion
    (B) Feathered: Chicken
  4. (A) Does not have fins: Snake
    (B) Has fins: Pomfret