An Introduction to Chemical Defenses

Chemical EcologySpring 2009

By: Melissa CsikariTiffany Dunn

Michael MourouzisKristina Orange

What is a chemical defense?

• A chemical defense is a secondary metabolite that exists to protect an organism from danger.– A “secondary metabolite” is

a chemical that is not needed for the normal metabolic activity of the plant or animal.

– Perhaps the most well known chemical defense is the thiol relased from a scared skunk!

Who else does this?

• Skunks are not the only ones who use a chemical to protect themselves.

• Other animals include:– Some snakes– Many insects– Some sea creatures– Some frogs

(amphibians)

How do they do it?

• Well let me tell you it ain’t easy!– Takes time and energy

• There are two ways that they accomplish this:– They can synthesize (that

means make) their own– They can consume a food

source containing a toxin and allow it to accumulate or convert that food source into a toxin.

I don’t believe it for a second, How are they poisonous?

They can taste bad so nothing wants to eat them. (Spit it out, like grandma’s meatloaf)

They can bite and inject a poison (Duh! copperheads, steer clear)

They can fire at you (Like your girlfriend’s father did on your first date)

But that’s not all!

Give me an example!

The Pufferfish

Contain a neurotoxin that can be lethal to humans as well as many of their natural predators.

Give me another example!

Poisonous Dart Frog

Luckily, it has bright colors (aposematic coloration) warning you to stay away. As little as 136 micrograms is enough to kill me! That’s equal to a couple grains of salt. (1) Don’t get any ideas!

Is it just animals?

No. Plants need to be kept safe too! Watch out for all those vegans!

Poisonous Plants?

Yep: It can range from a simple itch

to diarrhea to death!

I want to know about the plant that causes diarrhea!

Wisteria sp. Causes GI (that’s gastrointestinal, AKA digestive, AKA multiple trips to the bathroom) upset for 24 hours (2).

I want to know about the one that will kill you!

Cycas revoluta- Extremely lethal and assumed to be very palatable by animals. Causes: GI upset to liver failure (3).

Is this the end? No, it’s just an appetizer!

• Fugu (Pufferfish) Anyone?!

Pictures

• Slide 1: http://www.cartoonstock.com/newscartoons/cartoonists/mbc/lowres/mbcn543l.jpg• Slide 2: http://www.cartoonstock.com/newscartoons/cartoonists/jlv/lowres/jlvn303l.jpg• Slide 3: http://www.cartoonstock.com/newscartoons/cartoonists/cga/lowres/cgan668l.j• Slide 4: http://www.cartoonstock.com/newscartoons/cartoonists/mho/lowres/mhon14l.jpg• Slide 5: http://filesll.fluxstatic.com/00B1263001800C6E00073EFBFFFF/633721273753017740• Slide 6:

http://animals.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/animals/images/primary/puffer-fish-puffed.jpg

• Slide 7: http://images.google.com/imgres?imgurl=http://to55er.files.wordpress.com/2009/03/blue_poison_dart_frog_arp.jpg&imgrefurl=http://to55er.wordpress.com/2009/03/07/madder-than-a-box-of-frogs/&usg=__VOUIjXvGp2zEDWLVvfYHjotiq-Y=&h=615&w=734&sz=664&hl=en&start=3&um=1&tbnid=VBoxLI0QAE_paM:&tbnh=118&tbnw=141&prev=/images%3Fq%3DPoisonous%2BDart%2BFrog%26hl%3Den%26sa%3DN%26um%3D1

• Slide 8: http://www.cartoonstock.com/lowres/dre0589l.jpg• Slide 9: http://www.rickveldman.com/images/yosemite_cartoon_01b.jpg• Slide 10: http://www.dkimages.com/discover/previews/958/50534425.JPG

• Slide 11: http://www.californiagardens.com/images/Cycas-revoluta.jpg• Slide 12: http://www.cartoonstock.com/lowres/ndi0789l.jpg

References:

• 1. Poison Dart Frog. Retrieved from: http://waynesword.palomar.edu/dartfrog.htm on April 5, 2009.

• 2. Common Plants that can cause poisoning. Retrieved from: http://www.mda.state.mn.us/plants/badplants/poisonplants.htm on April 5, 2009.

• 3. Cycas revoluta. Retrieved from: http://en.wikipedia.org/wiki/Cycas_revoluta

on April 5, 2009.