The Main Differences Between Chordates and Non-Chordates: Explained
Chordates and non-chordates are two major groups within the animal kingdom. While they share some similarities, there are significant differences between them that set them apart. Understanding these differences is crucial for students of biology, animal science, and related fields.
What Are Chordates?
Chordates are animals that have a notochord, which is a flexible rod-like structure that runs along their back. This notochord provides support and allows for movement. Chordates also have a dorsal nerve cord that runs along their backs and a pharyngeal gill slit. These three characteristics – notochord, dorsal nerve cord, and pharyngeal gill slit – are present in embryonic, larval, or adult stages of chordates.
Chordates are further sub-categorized into three groups: vertebrates, tunicates, and lancelets. Vertebrates are chordates that have a well-developed backbone or spinal column. Fish, amphibians, reptiles, birds and mammals are all vertebrates. Meanwhile, tunicates and lancelets are invertebrates that lack a backbone or spinal column.
What Are Non-Chordates?
Non-chordates are animals that lack the three distinctive characteristics of chordates. In other words, they don’t have a notochord, dorsal nerve cord, or pharyngeal gill slit. Non-chordates are much more diverse than chordates, and range from simple, single-celled organisms to complex creatures with specialized organs, like octopuses, crabs and insects.
There is an extensive array of non-chordate animals and they are categorized by physical structures they size, number of appendages, and their feeding mechanisms. For example, sponges belong to the phylum Porifera, while jellyfish and corals are part of the phylum Cnidaria.
Main Differences Between Chordates and Non-Chordates
The fundamental differences between chordates and non-chordates are clear. Apart from their shared characteristics, chordates differ from non-chordates in several significant ways:
– Nervous System: Chordates possess a dorsal nerve cord, which is absent in non-chordates. The dorsal nerve cord is a key feature that separates chordates from non-chordates.
– Reproduction: Chordates reproduce sexually, while non-chordates can reproduce sexually as well as asexually.
– Symmetry: The body of non-chordates is generally bilaterally symmetrical whereas symmetry does not apply in all chordates.
– Sensory structures: Chordates generally possess specialized sensory structures that can detect pressure, temperature, light and sound waves, while non-chordates lack these sensory structures.
– Feeding Mechanisms: Non-chordates have a wide variety of feeding mechanisms that separate them from chordates. For instance, Cnidarians have tentacles that they use to capture small animals while fleshy sponges use their abundant pores to filter water for tiny plankton.
In conclusion, Chordates and non-chordates are two different groups of animals in the animal kingdom. While they share some similarities, their differences set them apart. It’s essential for students to understand these differences since they are crucial to the classification of animals.
Table difference between chordates and non chordates
| Chordates | Non-chordates |
|---|---|
| possess a notochord | do not possess a notochord |
| exhibit bilateral symmetry | may exhibit bilateral or radial symmetry |
| have a dorsal nerve cord | do not have a dorsal nerve cord |
| exhibit metameric segmentation | may exhibit metameric or non-metameric segmentation |
| have a post-anal tail | do not have a post-anal tail |