Not all invaders… come from outer space…. Boston Harbor Curley School.
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Transcript of Not all invaders… come from outer space…. Boston Harbor Curley School.
Not all invaders…
come from outer space…
Boston Harbor
Curley School
Invasive Crabs in Invasive Crabs in the Boston the Boston
HarborHarbor
Invasive crabs are Invasive crabs are “exotic”“exotic”
not this kind of exotic…
Exotic species can be animals, plants, or even
microbes (microscopic!)
Exotic species are Exotic species are not not nativenative to the to the ecosystemecosystem
Meaning we’re not originally
from here
Where are we from?
Cows?Rice?Chickens?Apples?
Imagine life without these things!
So, how do exotics get So, how do exotics get here?here?
We introduced some of We introduced some of them them on purposeon purpose
Fact: Fact:
Over 98% of the U.S. food Over 98% of the U.S. food supply are introduced supply are introduced
plants/animalsplants/animals
Or…Or…We introduce them We introduce them
accidentallyaccidentally
For example, ballast water
is used to stabilize the
ship…
but can transport a huge aquarium of exotic life!
These exotics get dumped into local waters.
Ballast water line
Exotic DisasterExotic Disaster
When is an exoticWhen is an exotic invasiveinvasive??
When it spreads rapidly and When it spreads rapidly and out-competes native speciesout-competes native species
A Kudzu invasion blankets all other life
Invasive Invasive successsuccess::They have HIGH They have HIGH reproductivereproductive rates rates
A single female Asian Shore Crab can produce up to 200,000 eggs per year!
That’s twice the rate of native crabs
They leave They leave behind their behind their predators predators and and competitors.competitors.
They play by They play by a different a different set of rules.set of rules.
Invasive Invasive success:success:
Wild boar in the U.S.
Invasives can be Invasives can be harmful…harmful…
They threaten biodiversity
Fact: ½ of all species that are
“endangered” have been impacted by invasives
Many of these endangered species
become extinct
Natural ecosystems support a biodiversity of species
The arrival of an exotic like Purple Loosestrife…
…can alter an entire landscape.
Important Invasives Important Invasives of the Boston Harbor of the Boston Harbor
European Green Crab
Asian Shore Crab
Impacts of the InvadersImpacts of the Invaders
European Green European Green CrabCrab
Accidentally Accidentally introduced in 1817introduced in 1817
Consumes large Consumes large numbers of juvenile numbers of juvenile soft-shell clams and soft-shell clams and oystersoysters
Eats $44 million Eats $44 million worth of shellfish per worth of shellfish per year!year!
Impacts of the InvadersImpacts of the Invaders
Asian Shore CrabAsian Shore Crab First recorded in First recorded in
Mass. in 1988Mass. in 1988 Broad diet, disrupts Broad diet, disrupts
food webfood web Studies show as Studies show as
Asian Shore Crab Asian Shore Crab numbers go up, numbers go up, native crab native crab numbers are numbers are decreasing decreasing
Ranges of the Invasive Ranges of the Invasive CrabsCrabs
European Green CrabAsian Shore Crab
Boston
Boston
What What cancan WE do? WE do?What What shouldshould WE do? WE do?These are OUR islands.These are OUR islands.
Become Citizen
Scientists!
Not this…Not this…This kind of
science!
Skills you will need:Skills you will need: Ability to identify a crab’s specie Ability to identify a crab’s specie
and gender and gender
Let’s do it!
Identifying the European Identifying the European Green CrabGreen Crab
Five Spines behind each eye
Color - can be green, red, yellow, or brown
Triangular shaped body
Identifying the Identifying the Asian Shore CrabAsian Shore Crab
Large claws relative tobody size
Relatively square body
Striped legs
Three Spines behind each eye
Identifying the native Identifying the native Rock CrabRock Crab
Nine or more Spines behind each eye
Color - usually reddish brown
Triangular shaped body
Identifying Gender in CrabsIdentifying Gender in Crabs
Males have the “lighthouse”
Females are more circular
This rule works for other species of crab too.
Quick Quiz!Quick Quiz!
1.1. List two reasons invasive species can List two reasons invasive species can be very successful.be very successful.
2.2. The European Green Crab has __ spines The European Green Crab has __ spines behind each eye.behind each eye.
3.3. The Asian Shore Crab has __ spines The Asian Shore Crab has __ spines behind each eye.behind each eye.
4.4. The native Rock Crab has ___ spines The native Rock Crab has ___ spines behind each eye.behind each eye.
5.5. Male crabs have a _____________ shape Male crabs have a _____________ shape underneath. underneath.
6.6. Female crabs have a more __________ Female crabs have a more __________ shape underneath.shape underneath.
5
3
9+
lighthouse
circular