Book contents
- Understanding the Tree of Life
- Series page
- Understanding the Tree of Life
- Copyright page
- Reviews
- Epigraph
- Contents
- Foreword
- Preface
- Acknowledgments
- 1 Introduction to the Tree of Life: Drawing Trees and Why There Is No Trunk
- 2 Human Origins: We Are African … Mostly
- 3 Primates: Our Closest Living Cousins
- 4 Which Mammals Are the Most Primitive? None of Us
- 5 Birds Are Reptiles, Birds Are Theropod Dinosaurs
- 6 The Crawl Onto Land: Tetrapod Evolution and the Gain and Loss of Limbs
- 7 Which Fishes Are “Primitive”? Do Fish Even Exist?
- 8 Animal Evolution: Sponges and Comb Jellies Are Our Cousins
- 9 Plants, Animals, Fungi, and “Protists”: We Are Eukaryotes
- 10 Archaea Then Bacteria Are Our Most Distant Cousins
- Concluding Remarks: The Success, Importance, and Conservation of All Life
- Summary of Common Misunderstandings
- References and Further Reading
- Figure Credits
- Index
9 - Plants, Animals, Fungi, and “Protists”: We Are Eukaryotes
Published online by Cambridge University Press: 19 September 2025
Book contents
- Understanding the Tree of Life
- Series page
- Understanding the Tree of Life
- Copyright page
- Reviews
- Epigraph
- Contents
- Foreword
- Preface
- Acknowledgments
- 1 Introduction to the Tree of Life: Drawing Trees and Why There Is No Trunk
- 2 Human Origins: We Are African … Mostly
- 3 Primates: Our Closest Living Cousins
- 4 Which Mammals Are the Most Primitive? None of Us
- 5 Birds Are Reptiles, Birds Are Theropod Dinosaurs
- 6 The Crawl Onto Land: Tetrapod Evolution and the Gain and Loss of Limbs
- 7 Which Fishes Are “Primitive”? Do Fish Even Exist?
- 8 Animal Evolution: Sponges and Comb Jellies Are Our Cousins
- 9 Plants, Animals, Fungi, and “Protists”: We Are Eukaryotes
- 10 Archaea Then Bacteria Are Our Most Distant Cousins
- Concluding Remarks: The Success, Importance, and Conservation of All Life
- Summary of Common Misunderstandings
- References and Further Reading
- Figure Credits
- Index
Summary
According to Aristotle and Linnaeus, there were only two “kingdoms” – Plantae and Animalia. In the 1800s, Haeckel carved kingdom “Protista” off of Linnaeus’ Plantae. Kingdoms for Fungi and Bacteria (Monera) were later added. By the time I was in secondary school, I learned a five-kingdom system. The five “kingdoms” that I learned are still frequently used in biology lessons: animals, plants, fungi, protists, and bacteria. But we now know that a five-kingdom story is so simplified as to be misleading, and it tells us very little about the broad tree of life. Back then, in the 1900s, our limited understanding made things seem more simple, but recent DNA sequence data indicate that the groupings are much more complex.
The five-kingdom system was first proposed in 1969. (1) Animalia were multicellular creatures that eat other organisms. (2) Fungi were generally multicellular decomposers that fed by a network of filamentous cells. (3) Plantae included especially the land plants.
Keywords
Information
- Type
- Chapter
- Information
- Understanding the Tree of Life , pp. 153 - 167Publisher: Cambridge University PressPrint publication year: 2025
Accessibility standard: WCAG 2.0 A
Why this information is here
This section outlines the accessibility features of this content - including support for screen readers, full keyboard navigation and high-contrast display options. This may not be relevant for you.Accessibility Information
The HTML of this chapter
conforms to version 2.0 of the
Web Content Accessibility Guidelines
(WCAG), ensuring core accessibility principles are addressed and meets the basic
(A)
level of WCAG compliance, addressing essential accessibility barriers.
Content Navigation
Table of contents navigation
Allows you to navigate directly to chapters, sections, or non‐text items through a linked table of contents, reducing the need for extensive scrolling.
Allows you to navigate directly to chapters, sections, or non‐text items through a linked table of contents, reducing the need for extensive scrolling.
Index navigation
Provides an interactive index, letting you go straight to where a term or subject appears in the text without manual searching.
Provides an interactive index, letting you go straight to where a term or subject appears in the text without manual searching.
Reading Order & Textual Equivalents
Single logical reading order
You will encounter all content (including footnotes, captions, etc.) in a clear, sequential flow, making it easier to follow with assistive tools like screen readers.
You will encounter all content (including footnotes, captions, etc.) in a clear, sequential flow, making it easier to follow with assistive tools like screen readers.
Short alternative textual descriptions
You get concise descriptions (for images, charts, or media clips), ensuring you do not miss crucial information when visual or audio elements are not accessible.
You get concise descriptions (for images, charts, or media clips), ensuring you do not miss crucial information when visual or audio elements are not accessible.
Full alternative textual descriptions
You get more than just short alt text: you have comprehensive text equivalents, transcripts, captions, or audio descriptions for substantial non‐text content, which is especially helpful for complex visuals or multimedia.
You get more than just short alt text: you have comprehensive text equivalents, transcripts, captions, or audio descriptions for substantial non‐text content, which is especially helpful for complex visuals or multimedia.
Visual Accessibility
Use of colour is not sole means of conveying information
You will still understand key ideas or prompts without relying solely on colour, which is especially helpful if you have colour vision deficiencies.
You will still understand key ideas or prompts without relying solely on colour, which is especially helpful if you have colour vision deficiencies.
Structural and Technical Features
ARIA roles provided
You gain clarity from ARIA (Accessible Rich Internet Applications) roles and attributes, as they help assistive technologies interpret how each part of the content functions.
You gain clarity from ARIA (Accessible Rich Internet Applications) roles and attributes, as they help assistive technologies interpret how each part of the content functions.