Invertebrates VS Vertebrates – Marine life explained with the Reef Conservation in Koh Tao
The ocean is full of life, from the tiniest plankton to the largest whales. However, to help us better understand life underwater, we must be able to differentiate between these two groups of animals: Invertebrates and Vertebrates. To get to know and understand them better, we first need to understand the evolution of these organisms from the very beginning.
The Earth was formed about 4.6 billion years ago with the ingredients of dust, fire, and other gases. In those early days, Earth was too hot and toxic, so the only possible way for life to start was in the ocean. As explained in Chad Scott’s book Ecological Monitoring Program (2019), one of the successful forms of life was bacteria. Bacteria are simple; they are only single-celled organisms, and do not have a nucleus, but they are the most abundant and probably most important group of organisms on the planet. From then, multicellular organisms began to form.
So, what exactly are invertebrates and vertebrates? And how do we tell them apart?
Invertebrates are animals that have no backbone or spinal column. Many people may think invertebrates are not important, but every organism has a role in the ecosystem. For example, the Ramose Murex or Helmet Conch is a top predator for many other marine invertebrates, helping to keep their population under control. Hermit crabs on the other hand, are important detritivores, helping to break down decaying organic matter and recycle nutrients back into the ecosystem. Whether you’re scuba diving, freediving, or just snorkeling, you will definitely spot many marine invertebrates. Some examples of what you can see on Koh Tao are:
Platyhelminthes phylum: Flatworms
Cnidaria phylum: Jellyfish, so many types of soft and hard corals
Porifora phylum: Barrel sponges and many other sponges
Mollusk phylum: Nudibranch, giant clams and boring clams, octopus and cuttlefish
Cnidaria phylum: Sea stars like the Crown of Thorns seastar, sea cucumbers, sea urchins like the flower urchin
Arthropod phylum: Hermit crabs
Drupella sea snail
Crown of thorn sea stars
Some invertebrates are more flexible as they have no backbone, and most importantly, every creature evolved from them. However, a small tip is that some of the invertebrates have developed themselves by replacing a hard shell, known as an exoskeleton, or by utilizing a fluid-filled cavity to support their organs.
Vertebrates are the opposite of Invertebrates, which are animals that have a backbone or spinal column. For example, mammals, reptiles, birds, amphibians, and fish. Many evolutionary traits that us vertebrates have were developed in the invertebrate phyla, such as the central nervous system, digestive system, circulatory system, and complex eyes. There are plenty of marine vertebrates around the world, but we will focus only on what you can see in Koh Tao’s underwater world. Such as,
Whalesharks
Blacktip reef sharks
Stingrays like the Blue spotted ribbon tail ray and the Jenkins ray
Butterfly fish
Parrot fish
Groupers
Barracuda
Triggerfish
White-eyed moray eels
Green and Hawksbill sea turtles
Sea snake
At New Heaven Reef Conservation Program, we invite you to dive deeper into the fascinating world of invertebrates and vertebrates through our Ecological Monitoring Program (EMP). Koh Tao is home to an incredible variety of marine life, and this course is your chance to explore it up close. As a conservation diver, you’ll learn how to recognize different species, understand their roles in the ecosystem, and discover how every creature, big or small, plays a part in keeping our ocean healthy and thriving.
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