Biota

Exploring Nature

Classification of life

This project began as a way to label and organise my wildlife photographs and identify the species in them. What started as simple naming quickly became more complex, as I realised that grouping organisms is often just as challenging as identifying them.

Biological classification is not fixed. Advances in molecular genetics continue to reshape our understanding of evolutionary relationships, and as a result, names change and groupings are revised. There is a vast amount of information available — and not all of it agrees.

What follows is not a definitive account of taxonomy. These are notes I’ve made while trying to understand the systems well enough to organise my own photographs, and they may change as my understanding evolves.

Taxonomy and classification systems

The main structure used here follows the traditional Linnaean system, with ranked categories:

Domain → Kingdom → Phylum (or Division) → Class → Order → Family → Genus → Species

I find this system intuitive and practical for grouping organisms and navigating between related taxa.

Alongside this, modern biology increasingly uses a cladistic (phylogenetic) approach, which groups organisms into clades based on shared ancestry rather than fixed ranks. This method is widely used in academic literature and continues to influence how taxa are defined.

Prokaryotes and Eukaryotes

At the highest level, all cellular life is divided into two broad groups:

  • Prokaryotes — organisms without a membrane-bound nucleus or organelles
  • Eukaryotes — organisms with a nucleus and complex internal structures

This fundamental difference underlies the separation of the kingdoms used here.

Prokaryotes

The prokaryotic kingdoms include organisms without a nucleus. Although they dominate much of Earth’s biomass and ecology, my own photographs in this area are limited.

Bacteria →

Single-celled organisms without a nucleus, found in almost every environment. Although some cause disease, many are essential to life through processes such as nutrient cycling and decomposition.

Archaea →

These are distinct from bacteria at a molecular level. Some live in extreme environments, but many are widespread and common. Their classification continues to change as more is learned about them.

Eukaryotes

Eukaryotes are organisms with a nucleus and include all plants, animals, fungi and many single-celled organisms. This is where most of my photographs and observations sit.

Protozoa →

Mostly single-celled eukaryotes that are not plants, animals or fungi. This group has been redefined many times and is still treated differently by different classification systems. Slime moulds (phylum Mycetozoa) are included here.

Chromista →

A diverse group of eukaryotes that includes brown algae, diatoms and various moulds. Many organisms previously placed in Protozoa, Plantae or Fungi are now grouped here based on genetic evidence.

Plantae →

Multicellular, photosynthetic organisms including land plants and some green algae. These are further divided into vascular and non-vascular plants, and into seeded and seedless groups.

Fungi →

Includes yeasts, moulds and mushrooms. Fungi play key roles in decomposition and nutrient cycling, and their classification below kingdom level continues to evolve.

Animalia →

Multicellular organisms usually capable of movement at some stage of life. This kingdom includes a wide range of body forms and lifestyles, from simple invertebrates to complex vertebrates.

Animals are broadly grouped into vertebrates (birds, mammals, reptiles, amphibians and fish) and invertebrates (insects, spiders, molluscs and many others). My photographs cover several of these groups, with dedicated sections for the main vertebrate classes and for the insect orders I encounter most often.

Quick-links:
Birds | Mammals | Amphibians | Reptiles
Butterflies & Moths | Dragonflies & Damselflies | Beetles | Bugs

Some of the resources used for identification