Starfish are fascinating creatures, but what do they eat?
Most people don’t know much about starfish. They’re not the most popular animal in the ocean and it’s easy to see why. They have a long, fused together body with five arms (or rays).
This blog post will explore everything from how starfish get around on the ocean floor to what they actually eat.
Starfish Overview
Starfish are invertebrates. Invertebrate is the term for animals that do not have a backbone like fish, amphibians, reptiles, and mammals.
Starfish are one of the most unique types of invertebrates because they have such long arms compared to their bodies. Their scientific name (order) is Asteroidea which loosely translates to “star-like”.
The scientific order is broken up into two groups that are characteristically different. These two groups of starfish are the shallow water (benthic) sea stars and the deep-sea (pelagic) sea stars.
The benthic group can be identified by their white coloration, spiny rays, and 5-digited arms. These starfish are found on the seafloor and tend to live in areas that contain lots of sediment (mud) or rocks.
Pelagic sea stars can also be identified by their white coloration alongside spiny rays, but they only have five arms compared to the benthic group which usually has five or more arms.
The close relationship between benthic and pelagic sea stars is that they both are carnivorous (only eat meat).
A starfish’s mouth is located in the middle of its body underneath its central disc. Their mouth and anus create a straight line called a tube foot. The tube foot has tiny pores which are used to suck in food and expel waste.
The feet are used to create a suction designed to pull the starfish to their food source; they only move when they are hungry.
Starfish Digestion
The anatomy of a starfish is very specific when it comes to what goes where. Starfish have developed little teeth (called pedicellariae) over time which help them crush and break down their food.
These pedicellariae are found on the underside of their arms, and in some instances can move around to different locations. Starfish ingest both small arthropods (invertebrates with external skeletons such as crustaceans) and detritus (dead organic matter).
Once the starfish ingests food, it travels through their tube feet to their stomach and then to their esophagus. The starfish’s stomach is filled with pincers which crush down on the food piece by piece (this is similar to your own jaw biting down on something) in order for them to digest the food.
The food then travels down to the middle of their body where it ends up in an intestine.
Starfish have developed a special part called an intracoelom (body cavity) that is filled with fluid and helps break down waste for elimination. All of this means that starfish are able to digest both meat and detritus, which is pretty cool.
Starfish Feeding Habits
The benthic and pelagic starfish are carnivorous animals that feed on small arthropods, crustaceans, mollusks (snails and clams), worms, fish eggs, whale corpses, and even other starfish.
Starfish have a very interesting method of hunting for food. They wait on the seafloor for their prey to come by, then they use their tube feet to create suction which pulls them closer to their prey. Once close enough, the starfish will release its stomach pincers and begin eating.
You might not think that a huge starfish could attack something as big as a whale, but they can. After a whale dies and starts to decompose, little pieces of the carcass fall off into the water which is then eaten by other animals. Some of those animals then become food sources for starfish.
Many species of starfish are carnivorous and will attempt to eat anything they can fit into their mouths. The larger and more predatory starfish prey on smaller species of starfish, snails, clams, worms, mollusks, crabs (cranteids), sponges (homoscleromorphs), sea urchins (echinoderms), and even fish! This is an interesting phenomenon because it shows that even other starfish prey on eachother. It’s like a never ending cycle of when the predator becomes the prey…
What Starfish Eat in Aquariums
Just like in the wild, starfish should only ever be fed meaty foods. They can eat mussels, clams, live fish (such as goldfish), and any other meaty food item.
Many pet owners are confused about whether or not they can feed their starfish shrimp because it is both a crustacean and an arthropod. The answer is yes and no.
Some shrimps are fine for starfish to eat, but others are not. Feeding your starfish shrimp can be tricky because some species of shrimp (such as the blood-red shrimp) contain carminic acid which causes them to turn red when their bodies break down after being eaten.
Carminic acid is what makes the color red so it is in both the exoskeleton and circulatory system of these shrimp. If your starfish eats carminic acid, it can cause them to go into cardiac arrest!
This means that feeding your starfish shrimp is something you should be very careful about. Luckily, goldfish are great to feed to your starfish because they are easy to get and don’t contain any carminic acid.
Starfish Reproduction
The benthic and pelagic starfish reproduce sexually in order to reproduce offspring. The male starfish creates sperm which is deposited into the female’s water vascular system.
Her eggs are fertilized by the male when they meet up with their sperm, which then travels to the female’s arms. The eggs then travel down into her tube feet and into the seafloor where they will grow until they are ready to become baby starfish.
Starfish have an interesting reproductive process considering that since they only have one opening where waste is released, as well as sperm and eggs developed, how does all of this stuff stay inside of them?
When it comes to fertilization, the male’s sperm has to be deposited on the female starfish’s lower side (or underside) in order for her eggs to not get mixed up with her waste; it is simply a matter of anatomy.
Starfish can have up to 30,000 babies at once! It is taken care of by the mother for a couple of weeks until it is able to find food on its own.
Some Interesting Facts About Starfish
Why are Starfish not Fish?
Starfish do not have any scales which is one of the main characteristics that set a fish apart from other aquatic animals. They also don’t have gills or fins; those traits define a fish.
How Many Legs Do Starfish Have?
Most starfish have 5 legs (or rays) each that are connected to their bodies and go out in a star shape. The only exceptions are the Linckia starfish which have 10 legs each or the Actinopodidae family which also has 5.
The Oldest Living Starfish is 400 Years Old
The oldest living starfish is estimated to be at least 400 years old! That’s pretty incredible for something that doesn’t have a central nervous system and doesn’t have any blood flowing through its body.
Is a Starfish Dangerous?
The starfish is not dangerous to humans, but their predatory behavior can be considered dangerous.
Their diets consist of crabs, clams, mollusks, and other marine animals (such as coral reef organisms). This puts them into the same category as a shark or rattlesnake because they are all carnivores!
Can a Starfish kill you?
Starfish are not dangerous to humans. They aren’t going to attack you, but they do have what is known as a “sharp-stick” which means they can leave a painful sting if you happen to get pricked by one of their spines.
The only way that you can really be sure of avoiding being stung by a starfish is to not touch one. They are harmless in that they won’t kill you, but if you do get pricked by one of their sharp-sticks there will be pain involved.
Starfish Don’t Have Brains
Did you know that starfish don’t have brains? They respond to things based on stimuli and nerve endings. Starfish also don’t have blood flow as we do, in fact, they are more similar to earthworms than us!
Starfish Reproduce Asexually
They can be either male or female but they reproduce asexually (like sea stars).
Starfish Can Regenerate Their Entire Body
If your pet starfish is missing a limb, don’t worry! Starfish are able to grow limbs back after they fall off.
Starfish can regenerate their entire body (except the central disc) if it gets damaged or lost. This means that as long as you have one arm left on your starfish, it will eventually grow back into a complete and healthy starfish.
Their Organs Are Located Outside Their Body
This is a crazy fact that most people don’t know! The organs inside of the body are actually located outside of it. Since starfish can regrow their entire body, this means that if one arm gets cut off the central disc, the other arms will drag the missing arm back to its rightful place and then regenerate all the organs that were in that arm.
Conclusion
It’s clear that there are many things to learn about starfish. Whether you’re a pet owner or an ocean enthusiast, this blog post should have given you some new knowledge on these fascinating creatures of the sea.
Starfish are one of the most unique species on earth. They not only have a very strange appearance, but they also live in some extreme places and conditions! It is truly fascinating to learn about the things that they do and how their body works.
Starfish are definitely one of a kind!
