Content
- Starfish reproduction
- How are the starfish pairing?
- Is the starfish oviparous or viviparous?
- What is the asexual reproduction of the starfish?
- Starfish automation
- Starfish and asexual reproduction
Starfish (Asteroidea) are one of the most mysterious animals around. Together with urchins, urchins and sea cucumbers, they form the group of echinoderms, a group of invertebrates that hide at the bottom of the ocean. It is common to see them on rocky shores as they move very slowly. Maybe that's why it costs us so much to imagine how is the reproduction of theleashes.
Due to their way of life, these animals multiply in a very peculiar and interesting way. They have sexual reproduction, like us, although they also proliferate asexually, that is, they make copies of themselves. Want to know how? So don't miss this PeritoAnimal article about reproduction of starfish: explanation and examples.
Starfish reproduction
Starfish reproduction begins when there are ideal environmental conditions. Most of them reproduce in the hottest season of the year. Also, many choose high tide days. But what about the reproduction of the starfish? Your main type of reproduction is sexual and it starts with the search for individuals of the opposite sex.
these marine animals have separate sexes, that is, there are males and females, with some hermaphrodite exceptions.[1] Tracking the trails of hormones and other chemicals[2], the starfish are placed in the best places to reproduce. All types of starfish form small or larger groups called "spawn aggregations" where males and females come together. From this moment on, each species shows different pairing strategies.
How are the starfish pairing?
The reproduction of starfish begins when most individuals join together in very numerous groups to start a process of crawling on top of each other, touching and entwining their arms. These contacts and the secretion of certain substances cause the synchronized release of gametes by both sexes: females release their eggs and males release their sperm.
The gametes unite in the water, occurring the so-called external fertilization. From this moment on, the life cycle of the starfish begins. There is no pregnancy: embryos form and develop in water or, in a few species, on the parent's body. This type of pairing is called pseudocopulation, as there is physical contact but no penetration.
In some species, such as the sand star (typical archaster), pseudocopulation takes place in couples. One male stands on top of a female, interspersing their arms. Seen from above, they look like a ten-pointed star. They can stay like this for a whole day, so much so that they are often covered with sand. Finally, as in the previous case, both release their gametes and external fertilization takes place.[3]
In this example of the sand stars, although the pairing takes place in pairs, it can also take place in groups. In this way, they increase their chances of reproducing, as well as having several partners during the same reproductive season. Therefore, the starfish are polygamous animals.
Is the starfish oviparous or viviparous?
Now that we've talked about starfish and their reproduction, we'll take another very common question about them. Most of the starfish is oviparous, that is, they lay eggs. From the union of sperm and eggs released, a large amount of eggs are formed. They are usually deposited on the sea floor or, in a few species, in hatching structures that their parents have on their bodies. When they hatch, they don't look like the stars we all know, but planktonic larvae that swim adrift.
Starfish larvae are bilateral, that is, their bodies are divided into two equal parts (like us humans). Its function is to disperse across the ocean, colonizing new places. As they do this, they feed and grow until the time comes to grow into adults. For this, they sink to the bottom of the sea and suffer a process of metamorphosis.
Lastly, although it is very rare, we must mention that some species among starfish types are viviparous. It is the case of patiriella vivipara, whose offspring develop inside their parents' gonads.[4] In this way, when they become independent from them, they already have pentameric symmetry (five arms) and live at the bottom of the sea.
And speaking of starfish and their reproduction, maybe you might be interested in this other article about the 7 rarest marine animals in the world.
What is the asexual reproduction of the starfish?
There is a widespread legend that the sea stars can make copies of themselves dropping parts of their paws. Is this true? How does asexual starfish reproduction work? Before we find out we should talk about autotomy.
Starfish automation
Starfish have the ability to regenerate lost arms. When an arm is damaged in an accident, they can become detached from it. They also do this, for example, when a predator chases them and they "let go" of one of their arms in order to entertain him while they escape. Afterwards, they begin to form the new arm, a very costly process that can take several months.
This mechanism also occurs in other members of the animal kingdom, like the lizards, who lose their tails when they feel threatened. This action is called autotomy and is quite common in some starfish, such as the incredible star-of-the-sun (helianthus heliaster).[5] Furthermore, autotomy is a fundamental process for understanding how starfish reproduce asexually.
Starfish and asexual reproduction
Some species of starfish can regenerate the entire body from a detached arm, although at least a fifth of the central disk is retained. Therefore, in this case the arms are not detached by autotomy, but due to a fission or fragmentation process of the body.
Starfish have their bodies divided into five equal parts. Not only do they have five legs, their central disc is also pentamer. When the necessary conditions occur, this central disc breaks or cleaves in two or more parts (up to five), each with its corresponding legs. In this way, each part can regenerate the missing areas, forming an entire star.
Therefore, the newly formed individuals are identical to your parent, therefore, it is a type of asexual reproduction. This type of starfish reproduction does not occur in all species, but in many such as the Aquilonastra corallicola[6].
Now that you know how starfish reproduce, you might also find it interesting to know the types of snails.
If you want to read more articles similar to Starfish reproduction: explanation and examples, we recommend that you enter our Curiosities section of the animal world.