The key difference between starfish and brittle star stems from their mode of movement. Starfish move by tube feet whereas brittle star moves by flapping their arms in the form of walking.
Starfish and brittle star belong to the Phylum Echinodermata which consists of exclusively marine organisms. They belong to two different classes as Asteroidia and Ophiuroidea, respectively. They are very colorful organisms. Both these organisms are capable of living in the shallow waters. Moreover, both are either predators or scavengers.
CONTENTS
1. Overview and Key Difference
2. What is Starfish
3. What is Brittle Star
4. Similarities Between Starfish and Brittle Star
5. Side by Side Comparison – Starfish vs Brittle Star in Tabular Form
6. Summary
What is Starfish?
Starfish or sea star belongs to the class Asteroidea of the Phylum Echinodermata of the Kingdom Animalia. In fact, they are very colorful organisms. They are exclusively marine and are present mostly in the shallow seas. Furthermore, they show penta-radial symmetry and have five arms that radiate from the central disk. The number of arms per starfish may vary.
Figure 01: Starfish
Starfish has a complete digestive system with a mouth and an anus. They have two stomachs: the cardiac stomach and the pyloric stomach. They mainly depend on predation for their nutritional requirements. Moreover, they perform partial external digestion before ingesting the food into the system. Cardiac stomach performs external digestion whereas pyloric stomach performs the internal digestion. Starfish moves with the aid of tube feet. Tube feet consist of ampullae and parapodia and these structures also help the starfish in locomotion. Furthermore, they have a well-developed water vascular system. Starfish also have simple eyes and their arms have special light-sensitive receptors.
What is Brittle Star?
Brittle star belongs to the class Ophiuroidea of the phylum Echinodermata. They are also very colorful organisms and are exclusively marine. They are capable of surviving in both shallow and deep sea. Similar to starfish, the brittle star also shows penta-radial symmetry. They have distinctly separated long arms in the central disk area. These arms are long and brittle; as their name suggests, they break up very easily upon injury but also regenerates fast. The digestive system of brittle stars is incomplete. Although they have a mouth, an esophagus and a stomach, they do not have an anus. Thus, expelling of waste also takes place via the mouth. They are either scavengers or predators.
Figure 02: Brittle Star
Movements in brittle Star are not facilitated by the presence of tube feet. They do not have tube feet, ampullae or parapodia. Instead, they move by flapping their long arms. This is similar to a form of walking.
What are the Similarities Between Starfish and Brittle Star?
- Both starfish and brittle star belong to the Phylum Echinodermata of Kingdom Animalia.
- And, they show penta-radial symmetry.
- Also, both exclusively live in marine environments.
- Both are capable of living in shallow marine environments.
- Furthermore, they are predators.
- Besides, both are very colorful organisms.
What is the Difference Between Starfish and Brittle Star?
Starfish and Brittle star appear to be similar in their external appearance, both being very colorful. However, they belong to two different classes of Echinodermata: class Asteroidea and Ophiuroidea. The key difference between starfish and brittle star is the manner in which they move. Starfish uses tube feet to move whereas brittle star uses its long arms to move. Moreover, starfish have special features such as the presence of ampullae and parapodia whereas brittle star lacks those. Hence, this is also a difference between starfish and brittle star. Furthermore, the digestive system is also a major difference between starfish and brittle star. That is; the starfish has a complete digestive system whereas the brittle star lacks a complete digestive system.
The below infographic presents more information regarding the difference between starfish and brittle star.
Summary – Starfish vs Brittle Star
Star fish and brittle star are exclusively marine echinoderms. The key difference between starfish and brittle star is the mode of movement; starfish uses tube feet for their movement whereas brittle star moves using their long arms. Additionally, the starfish has a complete digestive system with both mouth and anus. In comparison, the brittle star only has a mouth and stomach; thus, their digestive system is incomplete. Also, starfish has short arms while brittle star has long arms. Besides, both starfish and brittle star are colorful marine organisms that mainly depend on predation for their nutrients. Thus, this summarizes the difference between starfish and brittle star.
Reference:
1. Wilkin, Douglas, and Jennifer Blanchette. “Types of Echinoderms.” CK, CK-12 Foundation, 17 June 2017, Available here.
2. Zubi. “Multi – Celled Animals (Metazoa) ECHINODERMS.” Echinoderms (Starfish, Brittle Star, Sea Urchin, Feather Star, Sea Cucumber), Available here.
Image Courtesy:
1. “Starfish 08 (paulshaffner)” By Paul Shaffner, Iringa, Tanzania – flickr.com (CC BY 2.0) via Commons Wikimedia
2. “Greenbrittlestar” By Neıl ☎ – self-made (CC BY-SA 3.0) via Commons Wikimedia