How does a starfish heal?

When a starfish sustains damage to one of its arms, the first step in the healing process involves the isolation of the injured arm. The starfish accomplishes this by severing the connection between the damaged arm and the central disc. This process, known as autotomy, allows the starfish to prevent the spread of infection or further damage to the rest of its body.

Step 2: Formation of a blastema

Once the damaged arm is isolated, the starfish begins to form a blastema, which is a mass of undifferentiated cells that will eventually regenerate the lost arm. The blastema forms at the site where the arm was severed and is composed of various types of cells, including stem cells, fibroblasts, and blood vessels.

Step 3: Cell proliferation and differentiation

Within the blastema, the stem cells undergo rapid proliferation, dividing and multiplying to increase their numbers. As the cells proliferate, they also begin to differentiate into specialized cell types, such as muscle cells, nerve cells, and skin cells. The differentiation process is guided by various signaling molecules and growth factors that regulate the development of the new arm.

Step 4: Tissue regeneration

As the differentiated cells organize and arrange themselves, they start to form the various tissues that make up the arm, including muscle, nerve, and connective tissue. The regeneration process involves the formation of new blood vessels, which supply oxygen and nutrients to the growing tissues. This results in the gradual development of a fully functional arm that closely resembles the original one.

Step 5: Completion of regeneration

The regeneration process in starfish can take several weeks to months, depending on the species and the extent of the damage. Once the new arm is fully regenerated, it regains its normal functionality, allowing the starfish to move, feed, and reproduce effectively.

It's worth noting that while starfish have remarkable regenerative abilities, there are limits to their regenerative capacity. If the damage is too severe or extensive, the starfish may not be able to regenerate the lost arm completely or may even succumb to the injury.