Here’s a riddle: What do you get in a cup filled with ocean water? I will tell you that it’s not just water.
Instead, you find the most magnificent bundles of tiny animals called zooplankton. Zooplankton are tiny animals that float in the top layer of the oceans coasts wherever the current takes them. They are floaters. Some have the ability to swim short distances, but in the grand scheme of the ocean, they don’t go very far.
In the field of biological science, zooplankton are very important to the ecosystem. They are a vital part of the food web in the ocean – larger animals eat them, then even larger animals eat the large animals and the list goes on.
Some Zooplankton are classified as larvae. These grow and go through metamorphosis into an adult. You can identify what the larvae will become in the adult version with identification guides, however, most larvae look completely different from their adult life stage. In some cases, it is a surprising metamorphosis journey from larvae into adulthood.
Brittle stars are a very close relative to the Sea stars. They are incredible creatures and can fit in the palm of your hand. The only larvae feature that remotely resembles the adult is the long “arms” that they both have.
Brittle stars have many ways of reproducing. Most commonly, males and females will release their eggs and sperm into the water (called Broadcast Spawning) and when they join (fertilization), they create larvae, such as the one below that eventually turns into an adult. Another option is called Brooding, where eggs are kept in a mother’s body until they are ready to crawl out, pretty similar to humans. The last way is called Regeneration, or asexual reproduction. Some arms may break off but they can grow a new body and arms, creating multiple new individuals.
Larvae and Adult Brittle Star (Photo Credit: Danielle Marcoux; Wikimedia Commons)
Crab reproduction is pretty interesting because the females hold onto their eggs in a little pouch in a flap in their abdomen until they hatch into the larvae you see below. They can increase the amount of babies that survive by protecting their eggs to develop enough until they will be able to better survive on their own. Such great mothers.
Notice that this particular species of crab larvae has amazingly large head parts. This is most likely to prevent anything from eating it before it metamorphoses into the adult. I wouldn’t want to mess with anything that has a sword for a head either.
Porcelain Crab Larvae and Adult (Photo Credit: Danielle Marcoux; Wikimedia Commons)
Here are more extraordinary examples of larvae and their adult forms:
Larvae and Adult of Barnacles (Photo Credit: Wikimedia Commons)
Polychaete worms have many ways they can reproduce and can be very complicated at times [For more information, see the link below]. However, I have noticed that the larva that I found looks almost identical to the adult, which is not explicitly what we have seen in the examples above.
Polychaete Worm (Photo Credit: Wikimedia Commons)
Compare the adult to the larva in this video that I recorded:
(Video credit: Danielle Marcoux)
I find it unbelievable how the larvae in some organisms can be so incredibly different from what it metamorphoses into.
The diversity seems endless.
For more fun with Zooplankton: http://marinebio.org/oceans/zooplankton/
For more fun with Polychate worms: http://www.nhm.org/site/research-collections/polychaetous-annelids/faqs
If you ever wanted to identify zooplankton larva, here is a good place to start: http://www3.laurentian.ca/livingwithlakes/wp-content/uploads/2012/06/Zooplankton-Guide-to-Taxonomy.pdf