Lesson 13. Habitat Lessons: Wetlands
Class Discussion: What are wetlands? Why are they important?
Wetlands can be covered in water all of the year or only part of the year. Wetlands are important to
clean and filter water, as wildlife habitat, and to store flood waters. (Why Are Wetlands Valuable handout)
There are different types of wetlands, including Ash woodland, emergent wetlands, ponds, shrub
wetlands, wet prairie, and vernal pools. (What Are Wetlands handout)
Class Discussion: Why are wetlands in the Willamette Valley threatened?
Invasive species: bullfrogs, crayfish, fish, Reed Canary grass, and nutria compete with natives.
Habitat loss: agriculture and urbanization drain wet areas for use by people.
Class Discussion: Who lives in the Willamette Valley wetlands?
Many reptiles, amphibians, birds, and mammals live in wetlands. Amphibians are the most reliant on
wetlands for habitat because part of their life cycle must occur under water.
Amphibians are cold blooded and hatch with gills but develop lungs as adults. They live both on land
and in water. Amphibians are a good indicator of an ecosystem’s health. Amphibians’ thin skins help
them drink and breathe, but also make them susceptible to environmental contaminants, particularly
agricultural, industrial, and pharmaceutical chemicals.
The Pacific tree frog, called Gudu-kut by the Kalapuya, has a complex life cycle that follows the rhythm
of the seasonal changes in the wetlands. Each winter, large, clay-lined puddles of water, called vernal
pools, form on the surface of the wet prairie. These seasonal ponds provide homes for the early period
of the Pacific tree frogs’ lives. Later, the frogs move throughout the wetlands where they provide an
abundant food source for other animals. Each spring, male Pacific tree frogs make their way to vernal
pools and call out their distinctive, two-syllable “krek-ek” in unison to attract females. Throughout the
year, the one-syllable “c c-r-r-ick” is used to let other males know they are near. Frogs stop calling if
something comes near or they can throw their voices, making them hard to find by following their call.
After mating, female frogs lay hundreds of clear eggs in jelly-like masses on submerged vegetation in
the safety of these seasonal ponds, each cluster contains 10 – 70 eggs. The eggs are fertilized after they
are laid. The jelly-like mass around the eggs offers protection and maintains moisture. Tadpoles hatch 25 weeks later. As they metamorphose they develop lungs and legs, changing from aquatic to terrestrial
animals. Vernal pools are safe nurseries for tadpoles as there are fewer predators, like fish and bullfrogs,
than in year-round ponds. The bullfrog is a non-native species that is very aggressive and can outcompete native species. As the vernal pools dry up in the summer, adult frogs leave the ponds and
aestivate - they go into a dormant state, hiding in burrows, old logs, and other protected places.
Long toed salamander - Adult long-toed salamanders have extremely long toes on their hind feet and
black or brown skin that is smooth and moist with a yellow-to green-colored stripe running from its head
to the tip of its tail. It is speckled with white or silver dots along its sides and underside. Adults may
grow up to more than six inches in total length.
Lesson 13. Habitat Lessons: Wetlands
Long toed salamanders breed in ponds in late winter and then migrate away from the water to live as
adults. They live a subterranean life-style digging, migrating, and feeding on the invertebrates in forest
soils, decaying logs, small rodent burrows or rock fissures. They are carnivores, eating insects, tadpoles,
worms, beetles and small fish.
Rough skinned newt - Newts are a type of salamander, and so also lay their eggs in the water. Rough
skinned newts spend much more time in the water as adults than the long toed salamander, and during
breeding season you can often see them swimming near the bottom of shallow streams and ponds and
coming up for air every few minutes. They have a defense mechanism, a powerful neurotoxin, which
can kill most predators that try to eat them. The garter snake, however, has adapted to the toxin and is
the only predator that can eat this newt.
Review Questions:
What animals can you think of that live in wetlands in the Willamette valley?
What are the differences between reptiles and amphibians?
How can frogs indicate the health of a wetland?
Worksheet & Activity: Hand out the Why are Wetlands Valuable and What Are Wetlands info sheets
and have students volunteer to read each section. Create ID cards or notes on a few key wetland species.
Vocab:
Vernal -spring
Aestivate – to go dormant during the dry hot months
Aquatic - water
Terrestrial - land
Metamorphose – to physically change from one life stage to the next
Migrate – to move back and forth between 2 areas
Subterranean – underground
Defense mechanism – an adaptation that deters predators from eating an organism.
Teacher resources:
http://oregonstate.edu/~wilsomar/Persp_Plants.htm