Today, your first task will be to correct the quiz you took on Friday. Please review any questions that you had wrong, making sure that you understand what the correct answer is for that question.
Water striders live on the surface of ponds, slow streams, marshes, and other quiet waters. They eat living and dead insects on the surface of the water. Some are aquatic (water) insects, such as mosquito larvae coming up from the bottom, and others are terrestrial (land) insects, such as butterflies or beetles that accidentally land on the surface. Injured dragonflies are a favorite food, as are worms that fall in the water. Water striders have a sharp mouthpart, called a rostrum, to suck up body juices from prey.
Water striders have very good vision and move quickly on the water. The short front legs of a water strider are for grabbing prey. The middle legs push the insect forward, and the hind legs steer. The shape of their legs and their light weight keep them from breaking through the surface.
In breeding season, water striders communicate by sending ripples to each other on the surface of the water. Females lay eggs at the water's edge, usually on plant stems. When eggs hatch, nymphs (baby striders) must grow for over a month before they become adult water striders.
Water striders must always keep moving to so they don't become prey themselves to fish or other predators. They do not have wings and prefer the protection of overhanging trees and shade. They can live for many months, and adults can overwinter. They can crawl inside a plant stem when it gets too cold.
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Your assignment for today focuses on changes that occur in a forest ecosystem over a period of time. We call this process of change forest succession. (When we study other ecosystems such as ponds, we'll find that succession also takes place in many other types of habitats.)
Please access the website below to learn more about PA forest succession and some of the wildlife that are adapted to each stage. I would encourage you to take some notes and become familiar with terms like pioneer species, vertical structure, canopy...and any other terms that might be new to you. The site is found at: http://www.envirothonpa.org/documents/ForestSuccession.pdf
(You may wish to print out these two pages. If you read them on-line, click on the page and then use the + sign on the drop-down bar at the top of the screen to increase the size of the print to make it readable.)
1. "Leaves of three; let them be" is the best known and most useful cautionary rhyme. (This is also true of poison oak.)
2. "Hairy vine, no friend of mine." (As poison ivy grows up a tree if sends out hairy, root-like structures to cling to the bark of the tree.)
3. "Berries white, run in fright" (Poison ivy produces white berries.)
Here are some tips to help in preventing exposure to poison ivy:
-Wash your garden tools and gloves regularly. If you think you may be working around poison ivy, wear long sleeves, long pants tucked into boots, and impermeable gloves.
-Wash your pet if it may have brushed up against poison ivy, oak, or sumac. Use pet shampoo and water while wearing rubber gloves, such as dishwashing gloves. Most pets are not sensitive to poison ivy, but the oil can stick to their fur and cause a reaction in someone who pets them.
-Wash your skin in soap and cool water as soon as possible if you come in contact with a poisonous plant. The sooner you cleanse the skin, the greater the chance that you can remove the plant oil or help prevent further spread.
If you do get a poison ivy rash:
-Don’t scratch the blisters. Bacteria from under your fingernails can get into them and cause an infection. The rash, blisters, and itch normally disappear in several weeks without any treatment.
You can relieve the itch by:
- Using wet compresses or soaking in cool water.
- Applying over-the-counter (OTC) topical corticosteroid preparations or taking prescription oral corticosteroids.
- Applying topical OTC skin protectants, such as zinc acetate, zinc carbonate, zinc oxide, and calamine dry the oozing and weeping of poison ivy, poison oak, and poison sumac. Protectants such as baking soda or colloidal oatmeal relieve minor irritation and itching. Aluminum acetate is an astringent that relieves rash.
See a doctor if:
- You have a temperature over 100 degrees Fahrenheit.
- There is pus, soft yellow scabs, or tenderness on the rash.
- The itching gets worse or keeps you awake at night.
- The rash spreads to your eyes, mouth, genital area, or covers more than one-fourth of your skin area.
- The rash is not improving within a few weeks.
- The rash is widespread and severe.
- You have difficulty breathing.
Poison ivy and other poison plant rashes can’t be spread from person to person. However, it is possible to pick up the rash from plant oil that may have stuck to clothing, pets, garden tools, and other items that have come in contact with these plants. The plant oil lingers (sometimes for years) on virtually any surface until it’s washed off with water or rubbing alcohol.
The rash will occur only where the plant oil has touched the skin, so a person with poison ivy can’t spread it on the body by scratching. It may seem like the rash is spreading if it appears over time instead of all at once. But this is either because the plant oil is absorbed at different rates on different parts of the body or because of repeated exposure to contaminated objects or plant oil trapped under the fingernails. Even if blisters break, the fluid in the blisters is not plant oil and cannot further spread the rash.
Also today I'd like to highlight a unique type of forest habitat found in PA...called "old growth" forests. Please view this video and learn about Pennsylvania's "Forgotten Giants"....perhaps you have had the opportunity to visit one of the places that are shown in this video.
The eastern gray squirrel is a scatter-hoarder; it hoards food in numerous small caches (a small stockpile of food) for later recovery. Some caches are quite temporary, especially those made near the site of a sudden abundance of food which can be retrieved within hours or days... for reburial in a more secure site. Others are more permanent and are not retrieved until months later. Each squirrel is estimated to make several thousand caches each season. The squirrels have very accurate spatial memory for the locations of these caches, and use distant and nearby landmarks to retrieve them. Smell is used partly to uncover food caches, and also to find food in other squirrels' caches.
Squirrels sometimes use deceptive behavior to prevent other animals from retrieving cached food. They will pretend to bury the object if they feel that they are being watched. They do this by preparing the spot as usual, for instance digging a hole or widening a crack, miming the placement of the food, while actually concealing it in their mouths, and then covering up the "cache" as if they had deposited the object.
The eastern gray squirrel is one of very few mammalian species that can descend a tree head-first. It does this by turning its feet so the claws of its hind paws are backward-pointing and can grip the tree bark.
Eastern gray squirrels build a type of nest, known as a drey, in the forks of trees, consisting mainly of dry leaves and twigs. Males and females may share the same nest for short times during the breeding season, and during cold winter spells, squirrels may share a drey to stay warm. They may also nest in the attic or exterior walls of a house, where they may be regarded as pests, and as fire hazards due to their habit of gnawing on electrical cables. In addition, squirrels may inhabit a permanent tree den hollowed out in the trunk or a large branch of a tree.
Eastern gray squirrels are crepuscular, or more active during the early and late hours of the day, and tend to avoid the heat in the middle of a summer day. They do not hibernate.
Today, we'll begin to transition our attention from the topic of forestry, to the topic of soil. (You'll notice that these two topics are really interconnected, and that we'll come back to forestry concepts from time to time.)
First, I'd like you to learn a bit about the composition of soil...what it contains. The following website describes the components of soil. The website is located at this location (you'll need to click on the "next" arrow to see all 3 pages of the website):
Next, please read and study the background information and illustration below. This picture shows something called a "soil profile". It is like a cross-section view of the layers found at a particular place. Full soil profiles usually require a backhoe to remove soil, making a pit with the exposed layers (called "horizons") showing on the sides. I encourage you to make note (in your notebook) of any new terms or vocabulary you read in this lesson.
If you look in a soil pit or on a roadside cut, you will see various layers in the soil. These layers are called soil horizons. The arrangement of these horizons in a soil is known as a soil profile. Soil scientists, who are also called pedologists, observe and describe soil profiles and soil horizons to classify and interpret the soil for various uses.
We can easily notice differences in the various soil horizons (layers)...such as differences in color, texture, structure, and thickness. Other properties are less visible. Properties, such as chemical and mineral content, consistence, and reaction require special laboratory tests. All these properties are used to define different types of soil horizons.
Soil scientists use the capital letters O, A, B,and C, to "name" the horizons. Most soils have three major horizons---the surface horizon (A), the subsoil (B), and the parent material (C).
Some soils have an organic horizon (O) on the surface. Hard bedrock underneath (which is not soil) is given the letter R.
View this short video to hear more about these layers (in cartoon format!): https://www.youtube.com/watch?v=bgqea0E2eAY
Since we are beginning a study of soil, I thought it appropriate to feature the earthworm today. Folk names for the earthworm include "dew-worm", "rainworm", "night crawler", and "angleworm" (due to its use as fishing bait).
Recent research has suggested that even poor soil may support 250,000 earthworms per acre, while rich fertile farmland may have up to 1,750,000 earthworms per acre... meaning that the weight of earthworms beneath a farmer's soil could be greater than that of the livestock upon its surface!
Earthworms are very beneficial in improving soil quality. They do this several ways:
1.) In many soils, earthworms play a major role in the conversion of large pieces of organic matter into rich humus, thus improving soil fertility. This is achieved by the worm's actions of pulling below the surface deposited organic matter such as leaf fall or manure, either for food or to plug its burrow. Once in the burrow, the worm will shred the leaf and partially digest it and mingle it with the earth. Worm casts (waste excreted by a worm) can contain a high percentage of humus.
2.) The earthworm's burrowing creates a multitude of channels through the soil and is of great value in maintaining the soil structure, and enabling aeration and drainage.
3.) In addition to dead organic matter, the earthworm also ingests any other soil particles that are small enough—including sand grains up to 1/20 of an inch—into its gizzard, wherein those tiny fragments of grit grind everything into a fine paste which is then digested in the intestine. When the worm excretes this in the form of casts (worm feces....pictured below), deposited on the surface or deeper in the soil, minerals and plant nutrients are changed to form of the chemicals that plants are able to use.
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Today I'd like you to view this video which provides a good overview describing what soil is made of and how it forms. Make notes (in your notebook) ofideas and words that are new to you: https://www.youtube.com/watch?v=I3A7OnTLSM8
Today I would also like you to take some time to review the notes you have taken in the first few weeks of our Environmental Science class. Read over the things you have written about the "creature feature" species we have focused on, as well as your notes from the forestry unit.
We'll continue our look at soils tomorrow.
Since we are learning about soil, let's focus today on a creature that spends its life underground...the eastern mole. This common mole is very well suited for life underground. Its large, hairless, spade-shaped front feet are adapted for digging. It digs both deep, permanent burrows and shallow, temporary ones just under the surface, used for foraging for food.
The mole has fleshy, moveable snout projecting over its mouth with nostrils on the upper part. This snout is used as an organ of touch. Its tiny eyes are hidden in the fur; the eyelids are fused and its sight is limited to simply distinguishing between light and dark. The ear opening is small and concealed in the fur, but the mole has fairly acute hearing.
The eastern mole is voracious eater and will daily consume food equal to 25 to 100% of its weight. In captivity, it will eat almost anything, including ground beef and dog food. In its natural environment, it feeds mainly on earthworms when these are available, but will eat many other foods, including slugs, snails, centipedes, larval and adult insects, beetle grubs, and ants. Plant matter may also be consumed.
Moles feeding in a grassy area may leave behind a trail of small tunnels across the yard. When digging new burrows, the mole will push excess soil up through vertical shafts called "molehills".
Dogs, cats, foxes, and coyotes prey upon the mole, and it may host a variety of parasites.
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Let's continue our study of soil today...
When soil scientists (pedologists) analyze soil, they look at many characteristics of the soil. They measure the depth of each horizon. They examine the soil structure, color, texture, density and chemical makeup of each horizon. Based on these characteristics, the soil is classified.
When soil scientists (pedologists) study the soil in a particular place, they often conduct a soil survey of that area. To complete a soil survey, the scientists systematically examine, describe, classify, and map the soils in that area. These soil survey reports are published by the National Cooperative Soil Survey and are available to everyone. The National Cooperative Soil Survey identifies and maps over 20,000 different kinds of soil in the United States. Most soils are given a name, which generally comes from the location where the soil was first mapped. Named soils are referred to as soil series. Some examples of names of soil series found in our area include Berks, Bowmansville, Brecknock, Conestoga, Chester, Lehigh, Manor and Pequea.
Soils are named and classified on the basis of physical and chemical properties in their horizons (layers). Soils and their horizons differ from one another, depending on how and when they formed. As we already read in one of our lessons last week, soil scientists use several soil factors to explain how soils form.
1.) Parent material - this is the underlying rock that is found under the soil layers. In Lancaster and Berks counties, this is often sandstone or limestone.
2.) climate - Soils vary, depending on the climate. Temperature and moisture amounts cause different patterns of weathering and draining. Wind can redistribute sand and other particles. The amount, intensity, timing, and kind of precipitation influence soil formation. Seasonal and daily changes in temperature affect moisture, activity of living organisms in the soil, rates of chemical reactions, and kinds of plants that grow in that soil.
3.) topography - Slope or "lay of the land" affect the moisture and temperature of soil. Steep slopes facing the sun are warmer, just like the south-facing side of a house. Steep soils may be eroded and lose their topsoil as they form. Thus, they may be thinner than more nearly-level soils. Deeper, darker colored soils may be expected on the bottom land.
4.) biological (living) factors - Plants, animals, micro-organisms, and humans affect soil formation. Animals and micro-organisms mix soils and form burrows and pores. Plant roots open channels in the soils. Different types of roots have different effects on soils. Grass roots are “fibrous” near the soil surface and easily decompose, adding organic matter. Taproots open pathways through dense layers. Micro-organisms affect chemical exchanges between roots and soil. Humans can mix the soil extensively. Leaves from plants fall to the surface and decompose on the soil. Organisms decompose these leaves and mix them with the upper part of the soil.
Lastly for today, I'd like you to view a video that touches on much of what we are learning about soil. It is about 30 minutes in length. I encourage you to view this video with the "closed caption" option turned on (so you can see the words that are being spoken). To turn it on, click on the "CC" at the bottom right corner of the video. Click here to begin: https://www.youtube.com/watch?v=Ego6LI-IjbY
Don't forget to take the Week #4 Quiz today... and enjoy a nice, autumn weekend!