From Marlin to Marilyn: Clownfish Change Their Genders! Bizarre Courtship and Mating Rituals in the Animal Kingdom

Clown_fish_in_the_Andaman_Coral_Reef

Clownfish in anemone home

It turns out Finding Nemo had it wrong.  When a barracuda ate mom in the first scene of the movie, Marlin would not become a single dad, because being a single dad clownfish is impossible.  Realistically, Marlin would have become Marilyn– a single mom!

Clownfish are protandrous sequential hermaphrodites.  In other more pronounceable words, clownfish start their lives as males and then change into females.  Why is this necessary?

Clownfish2

Clownfish live in sea anemones and have adapted so they are unharmed by the anemone’s stings.  Because of its unique mutualistic relationship with the anemone (the clownfish eat parasites off the anemone, effectively cleaning it), the clownfish is reluctant to wander too far beyond its tentacly home.  This becomes problematic when the clownfish wants to meet members of the opposite sex, so the clownfish has evolved an interesting mechanism – sequential hermaphroditism – to overcome this obstacle.

Nemo

Marlin and Dory from Finding Nemo movie

Instead of braving the dangerous open waters beyond the reef (no, neither Marlin nor Nemo would realistically breach the “drop-off” and make it back alive), all the clownfish living in one place are males except the oldest, which is always a female.  After the head female dies, the next-oldest male turns into a female!

I suppose Pixar would’ve had a hard time explaining why they turned Marlin into Marilyn after one scene – I would’ve been confused too.  But in reality, the animal world of romance hosts a plethora of bizarre courtship behaviors, mating rituals, and other such oddities that put human courtship to shame!

References:

Clownfish picture 1 by ecatoncheires on Flickr: http://www.flickr.com/photos/ecatoncheires/2335044473/.

Nemo picture: from Cthomasuscg on Flickr:  http://www.flickr.com/photos/cthomasuscg/3304908183/

Interesting animal romance behaviors:  http://www.care2.com/greenliving/animal-romance-they-have-sex-how.html?page=1.

“Sequential hermaphroditism.”  Wikipedia.org:  http://en.wikipedia.org/wiki/Sequential_hermaphroditism

Clownfish information at Shedd Aquarium:  http://sea.sheddaquarium.org/sea/fact_sheets.asp?id=72

Clownfish information at Visit Sea Life:  http://www.visitsealife.com/explore-our-creatures/clownfish.aspx

Clownfish information at Evolution Faq:  http://www.evolutionfaq.com/articles/sex-change-nature-coral-reef-fish

Lions, tigers, and bears, oh my! What is a keystone species and how can conservationists use them?

Lion (Panthera leo)

tiger cub

Tiger (Panthera tigris)

Grizzly bear (Ursus arctos horribilis)

Grizzly bear (Ursus arctos horribilis)

What do these three animals have in common?  No, it’s not that they’re all featured in a popular film.  It’s not even that they’re all at the top of the food chain, although that’s closer.  Lions, tigers, and bears are all keystone species.

In architecture, the keystone at the top of an arch holds the arch together.  Without the keystone, the whole arch and building surrounding it will collapse.  Similarly, “keystone species” are animals that have a disproportionately large effect on the ecosystems they live in.

For example, Robert T. Paine first tested the keystone species hypothesis empirically (scientifically) by removing a species of starfish (Pisaster) from its intertidal habitat and observing the dramatic changes this removal wrought on the starfish’s prey, mussels (Mytilus) and the ecosystem as a whole.  It turns out that the starfish helped to keep the mussels’ numbers in check, and without the starfish to eat the mussels, the mussel population exploded and took over the habitat, crowding out other species and decreasing biodiversity (the numbers of different species in an ecosystem).

Keystone species can fall under several different categories.  Top predators, like the starfish, are often keystone species because of the inherent role they play by eating lots of smaller animals.  That’s why it’s so important to conserve large mammalian carnivores like lions, tigers, and bears – all endangered species – which unfortunately attract a lot of poaching due to their magnificent furs and sought-after meat.

arch1

Another category of keystone species are mutualists, which are animals that help many other species for something in return (in a mutually beneficial relationship).  For example, fruit trees are keystone mutualists because they provide shelter and food for many animals like monkeys and birds, which repay the tree by dispersing their seeds far and wide.

Finally, ecosystem engineers are keystone species because they are animals that change the physical landscape in which they live.  Beavers, elephants, and prairie dogs are all examples of ecosystem engineers because they build dams, destroy trees, and make burrows, respectively.

Prairie_Dog_closeup

Prairie dog (Cynomys)

Learning about these concepts helps scientists and environmentalists define categories in which to place animals and know which animals to target in conservation efforts.  It is far easier to conserve a whole ecosystem by protecting one species than by trying to protect the entire community of animals.  In this way, scientists use keystone species to protect Mother Nature, one animal at a time!

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References:

See No Ordinary World’s post on sea otters, another important keystone species:  https://thisisnoordinaryworld.wordpress.com/2013/03/06/sea-otters-adorable-endangered-and-a-keystone-species/.

Keystone species definition: http://animals.about.com/od/animalswildlife101/f/keystonespecies.htm.

“Keystone.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Keystone_(architecture).

“Keystone Species.” Marietta.edu.  http://www.marietta.edu/~biol/biomes/keystone.htm.

“Keystone Species.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Keystone_species.

“Mutualism.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Mutualism_(biology).