Ecosystems:
Lesson 1: Symbiosis
Textbook pages D 54-61
Critical Vocabulary: Competition, cooperation, symbiosis, mutualism, commensalism, parasitism.
Critical Content:
® Competition: In nature, competition is the struggle between individuals or different populations for a limited resource. Competition can occur between members of the same species or between members of different species.
® Cooperation: An interaction in which organisms work in a way that benefits them all. Cooperation, like competition, can occur between members of the same species or between members of different species.
® Symbiosis (means “living together”): The relationships between individuals of two different species who live together in a close relationship. There are three different types of symbiotic relationships:
o Relationships that benefit both partners
o Relationships that benefit one partner while doing no harm to the other.
o Relationships that benefit one partner while the other is harmed.
® Mutualism: An interaction between two species that benefits both. (Example: The relationship between birds and flowers.)
® Commensalism: A relationship between two species in which one species benefits while the other is not affected. (Example: The relationship between remoras and sharks.)
® Parasitism: A relationship between two species in which one species benefits while the species it depends on (called a host) is harmed. Parasites often feed off of and weaken their hosts. (Example: The relationship between ticks and dogs.)
CRISS Strategy: Main Idea Mapping
(Introduction sheet that can be used with students is attached)
à One of the things that sixth graders are taught in Language Arts is writing clear main ideas and supporting those main ideas with details.
à Identifying main ideas and supporting details while reading, therefore, supports this process.
à In main idea mapping, students are given a main idea and asked to find three or four supporting details. Detail categories can include—but are not limited to—examples, reasons and explanations.
à As students become more experienced, teachers can leave the “main idea” box blank, asking students to identify that as well.
Lesson Body:
(needed materials: computer with internet connection and data projector, copies of “Main Idea Mapping” viewing guide [attached], copies of current event articles displaying the three types of symbiotic relationships.)
à Begin by sharing the current event titled “Tongue-Eating bug found in fish” with students: http://bbc.in/tonguebug Consider using a data projector to do this as the image shared in the online article is engaging.
à Explain that this animal demonstrates that species in nature interact with each other in interesting ways. Today’s lesson is about exploring the kinds of interactions that plants and animals have with one another.
à Begin by reviewing the “Main Idea Mapping” reading strategy sheet (attached). Discuss with students the types of supporting details that authors use to develop main ideas.
à Ask students to complete the attached Main Idea Maps while reading pages D 54-61. Consider allowing students to work with a partner while reading.
à If necessary, pair strong readers with weaker readers. Also, if time is a concern, assign one section of text to small groups of students and have groups teach their main idea to the class when reading has been completed.
à Review Critical Vocabulary with students. Have students review their supporting details with one another. Review answers with the entire class. Ensure that students have found significant supporting details.
à Then, hand out copies of the remaining current event articles that demonstrate the symbiotic relationships between species. Have small groups of students work together to identify the types of relationships modeled in each article.
Additional Current Event Titles (answer key):
® Zombie Worms found off Sweden: (commensalism)
® Bumblebee campaign causes a buzz: (mutualism)
® Bees under threat: (parasitism)
Section Assessment Question (optional):
Oftentimes, relationships between middle school students can be described as symbiotic. Can you give some examples of mutualistic, commensalistic and parasitic relationships between friends?
Main Idea Mapping
Good readers are always able to pick out the main idea in selections of text. “What is this piece mostly about?” they wonder. “If I had to give just one word that best describes this selection, what would it be?”
Good readers are also able to find details that support main ideas. “What are the most important things to know about this section of text?” they’ll ask. “If I had to teach this material to someone in another class, what would I want to share?”
One way to “get good” at identifying main ideas and supporting details is to make a main idea map. Main idea maps look like this:
Here’s an example of a completed main idea map:
Reading Guide: Symbiosis
Student Name: ______
While reading lesson 2.2 in your textbook (pages D 54-61) fill in supporting details on the following main idea maps. Remember that supporting details could be reasons, explanations or examples.
'Zombie worms' found off Sweden
A new species of marine worm that lives off whale bones on the sea floor has been described by scientists.
The creature was found on a minke carcass in relatively shallow water close to Tjarno Marine Laboratory on the Swedish coast. Such "zombie worms", as they are often called, are known from the deep waters of the Pacific but their presence in the North Sea is a major surprise.
Adrian Glover and Thomas Dahlgren tell the journal the new species has been named Osedax mucofloris , which literally means "bone-eating snot-flower".
"They look like flowers poking out of the whale bone. The analogy goes a bit further because they have a root system that goes into the bone," Dr Glover, a researcher at London's Natural History Museum, told the BBC News website.
"The part of the animal that is exposed to the seawater is covered in a ball of mucus, so they are quite snotty. That is probably a defence mechanism."
Global distribution
Scientists have recently begun to recognise the importance of "whale fall" to ocean-floor ecosystems.
When the great marine mammals die and drift down to the sea bed to decay and disintegrate, they provide a food resource for a host of different organisms. Finding these locations to study is not easy, though.
In October 2003, Glover and Dahlgren sank the remains of a dead, stranded minke whale in 120m of water and monitored what happened to the carcass over a period of months using remotely operated vehicles.
In August 2004, the team was able to recover a bone from the skeleton. To their astonishment, it hosted a type of marine worm previously only thought to exist at great ocean depths - down to almost 3km in the Pacific on the bones of gray whales.
Hunting impact
Osedax worms are about 1-2cm in length. They root themselves to the whale bones which they then plunder for oils with the help of symbiotic bacteria. The worms' flower-like plumes pull oxygen from the water.
This has given rise to the theory that whale falls may act as "service stops", or hopping points, that allow some lifeforms to move around the ocean floor.
What concerns researchers is that the commercial hunting which so devastated whaling populations would also have severely curtailed this movement by reducing the incidence of whale fall. It may even have led to the extinction of some bottom-dwelling organisms that depended on this rare but concentrated nutrient supply.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/4354286.stm
Bumblebee campaign causes a buzz
A campaign to save the bumblebee is causing a buzz among the UK's farmers.
Around 300 English farmers are backing a scheme--started by the grocery store Sainsbury’s--to save the creatures, whose numbers have fallen in recent years.
The farmers are going to grow plants and flowers which attract bumblebees to supply them with stuff called nectar and pollen that they need to survive. Currently, the fields and natural areas where these flowers used to grow have become barren as farmers use more and more pesticides to control bugs.
It's being seen as a very important step because bumblebee numbers have dropped as a result of their habitats being wiped out. It is also important for the farmers, as over 85% of the agricultural products that are grown by farmers rely on the pollination powers of the bumblebee.
It's hoped that this plan will be taken up by even more farmers who supply the supermarket chain in the future to guarantee that bee species don’t dwindle out completely.
Story from CBBC NEWSROUND:
http://news.bbc.co.uk/go/pr/fr/-/cbbcnews/hi/newsid_5290000/newsid_5290800/5290802.stm
Published: 2006/08/27 12:45:25 GMT
Bees 'under threat'
Bee-keepers in Kent and in Northern Ireland have warned their stocks could be under threat because of a pesticide-resistant parasite.
Honey bees in Northern Ireland face a new and potentially deadly threat following confirmation of the arrival of a virulent species of bug.
The parasite, the varroa mite, sucks the blood of bees, eventually killing its host. Bee expert Joseph Hutton explains:
"They introduce a paralysis virus which kills the adult bees within five to eight days. If there's only a few mites in the colony the number of bees that are going to be killed are very few.
"But when the colony reduces from 90,000 in July to 12,000 for the winter period and there's 2,000 varroa mites the results can be very serious."
Northern Ireland has about 800 registered bee keepers and probably the same number of people again who simply keep a hive in their garden.
The Department of Agriculture has confirmed that the varroa mite has been found at five locations and has declared north Down and the Ards peninsula an infected area.
Infestations can be treated, but once the mites become widespread there is little doubt there will be reoccurrence.
Insecticide strips can be used in hives to control the mites, but some honey producers may be reluctant to rely on chemicals in the production of honey.
Hives with even low levels of infestation produce relatively little honey as the mites drain the bees of energy.
Colonies carrying the varroa mite are particularly prone during the winter months with the mites leaving them in a weakened state.