Direct or Indirect Development in Chondrichthyes

Chondrichthyes, also known as cartilaginous fishes, include sharks, rays, and chimeras. These fishes have a unique mode of development, which is different from other fishes. The mode of development in Chondrichthyes can be either direct or indirect, depending upon the species. Let's discuss both types of development in detail.

Direct Development

Direct development is a type of development in which the embryo develops into a miniature version of an adult. The direct development occurs in some species of sharks, such as the great white shark, and in some species of rays, such as the electric ray. In these species, the embryo develops within the egg capsule, and the yolk sac provides nourishment to the embryo. The embryo does not go through the larval stage, and after hatching, it looks like a miniature version of an adult. The juvenile sharks and rays continue to grow and mature into adults.

Indirect Development

Indirect development is a type of development in which the embryo goes through a larval stage before developing into an adult. The indirect development occurs in most species of sharks, such as the hammerhead shark, and in all species of chimeras. In these species, the embryo develops within the egg capsule, and the yolk sac provides nourishment to the embryo. After hatching, the embryo develops into a larva, which is different from an adult in shape, size, and behavior. The larva feeds on plankton and other small organisms, and after a few months, it metamorphoses into a juvenile shark or chimera. The juvenile continues to grow and mature into an adult.

Conclusion

In conclusion, Chondrichthyes have a unique mode of development, which can be either direct or indirect. The direct development occurs in some species of sharks and rays, while indirect development occurs in most species of sharks and all species of chimeras. The mode of development is determined by the species and has an impact on the behavior and ecology of the fish.

In Chondrichthyes development is indirect because it involves larval stages in development.