Let's take a look at amphibians by Hands-On Education
Throughout our amphibian’s topic your child will learn about the key features of amphibians, find out what frogs eat and the stages of a frog’s life cycle. Explore a pond habitat and observe why amphibians live there, also discover how fully functional early life amphibians are compared to other animals. With seven great activities your students or home educated will love learning about the life cycle of an amphibian.
What is an amphibian?
All amphibians are cold blooded vertebrates once they reach their complete development stage and become terrestrial adults. Amphibians are primarily made up of frogs and toads, salamanders, crested newts and caecilian make up a variety of other aquatic and semi-aquatic amphibian species. It was recently diverged caecilians, a worm like mostly blind creature, allow their young to scrape off and eat a layer of their own skin as opposed to feeding them milk or bringing them food.
Another interesting scientific discovery, from 2008, revealed that butterflies can remember life as a caterpillar.
The life cycle of an amphibian always starts in the aquatic phase. Frogs will lay eggs in a pond or nearby body of water.
- This begins with aquatic larvae and represents the first of three changes within this animal’s body structure. The subsequent aquatic larvae transition brings a newly hatched tadpole to life.
- The tadpole’s aquatic lifestyle is in no way it’s complete development. As time passes their large external gills disappear and primitive lungs being to grow. This dramatic embryonic and larval development happens quickly in both newt larvae, frogs and toads.
- The third transition brings about the land phase of a frog and toads life cycle. Following this true metamorphosis, the parental body will spend the rest of its life near water but not living underwater. This wonderful biological process is shared in all the amphibian species and makes them truly unique.
Do vertebrates undergo metamorphosis?
Firstly, no mammals go through metamorphosis as they don’t have the required hormone and are born in largely the same form forever. Birds also cannot metamorphose, but insects, amphibians and fish can. Let’s look at what exactly these processes called metamorphoses are?
The biological process is effectively a type of animal development from one life cycle stage to another. However, unlike other types of typical amphibian development, the change is relatively fast and dramatic. The animal's body structure goes through a significant reorganization from how it was in the previous stage. The process that stimulates metamorphosis is controlled by a hormone release in the cells of the body, specifically, the hormone released to control the process is known as iodothyronine.
It is important to differentiate how vertebrates’ metamorphosis compare to other types of growth. In mammals, including humans, physical changes throughout adolescence are not a vertebrate metamorphosis at all. The development is gradual and the adult organism resembles its juvenile form, this is why no mammals go through metamorphosis. Birds mimic mammals in this as they are effectively born as miniatures of their terrestrial adult self.
There are different types of life cycle changes in animals which often require specific ecological circumstances. The three main distinctions are:
- complete metamorphosis
- partial metamorphosis
- no metamorphosis
There is still much we do not know about this fascinating type of development and it was recently discovered that even tunicates undergo metamorphosis. Another interesting scientific discovery, from 2008, revealed that butterflies can remember life as a caterpillar.
Regrowth of limbs in salamanders
A quick look now at how amazing salamanders are as the only living amphibian tetrapod’s able to regenerate their limbs. This animal physically develops in the same way as other amphibians, however its able to activate a process known as controlled cell death or programmed cell death which some believe is linked to their complete mitochondrial genomes. In extraordinary fashion salamanders can lose a tail or limb and through incredible regenerative cell growth developed fully reformed replacement.
The Australian Green Frog’s Life Cycles
Green frogs are most commonly found to live in eastern and south-eastern New South Wales. They live among vegetation in or at the edges of ponds, dams and streams. A green frog life stages follow a normal embryotic development within the class amphibia life cycle: egg - tadpole - metamorph - adult. As a functional common frog, they eat insects, spiders, small lizards, snakes, and other frogs. This predatory lifestyle does not come without its own risks as many of its prey can also turn predator upon them.
The Life Cycles of Newts
Every animal develops in unique ways, and amphibians are no exception to this rule. From animal reproduction, which in the case of newts occurs near a body of water. This means newt larvae start in water. Unlike frogs and toads who spend their adult life out of the water newts are semi-aquatic amphibians.
Lateral Line System in Fish
Molecular phylogenetics analyses genetic and hereditary molecular differences to gain information on an organism's evolutionary path. A fish’s evolutionary journey has led to the development of a lateral line organ that is crucial in their existence not only in the ocean but even in a fish tank. The lateral line system allows fish to detect the moment of waves in water. Thanks to this a fish can learn a lot about the world it is living in even if blind. For instance, when a fish swims, it creates a tiny wave which may run up against the glass of a fish tank or other plants and animals nearby. From this they can mentally paint a picture of the world around them.
Unlike the amphibian life cycles where there is complete transformation including the loss of gills and growth of primitive lungs, fish simply grow large external gills. In most fish, and a number of other aquatic animals the pulmonary respiration system consists of gills, which are either partially or completely external organs. Other animals, such as insects, have respiratory systems with very simple anatomical features.
