When unknown organisms are being classified, biologists begin by looking for analogies or anatomical structures that have the same function in other species. An example of this is the wings of a bird and the wings a butterfly. However, not all of these are from a common ancestor. It must be determined if these analogies are due to independent evolutionary development or come from a common ancestor. If analogous structures are close genetically, they are called homologies, meaning they are inherited by a common ancestor. In actual classification of species, listing characteristics that are similar or distinctive is a good way to start. Although, keep in mind that some of the traits are brought about by evolutionary processes that are continuing. These could be expected to give rise to new forms in the future.

In trying to define species from fossil records, morphological characteristics are the criteria for identification. The Linnaean scheme of classification of living organisms puts them together based on presumed homologies. The assumption is, the more homologies organisms share, the closer they must be related. The identification of organisms is classified down to Genus and Species. However, an organism can be classified to any level of choice: Phylum, Class, Order, Family, Genus, and Species. When doing this activity, it is sufficient to classify organisms to the Phyla in which they belong. Reference: http://daphne.palomar.edu/animal/default.htm

All life forms are grouped into three different domains based on certain characteristics. These three domains are Eubacteria, Archaea, and Eukaryotes. All the information on domains below is from Wayne Maddison and his Tree of Life: http://phylogeny.arizona.edu/tree/life.html

The relationship among the three domains: Eubacteria ("True bacteria", mitochondria, and chloroplasts) | Archaea (Methanogens, Halophiles, Sulfolobus, and relatives) | Eukaryotes (Protists, Plants, Fungi, Animals, etc.) ? Viruses

The monophyly of Archaea is controversial. Two alternative views on the relationship of the major lineages (omitting viruses) are shown below:

The "archaea tree": ,=============== Eubacteria | | ,== Euryarchaeota =====| ,=Archaea=| `==| `== Crenarchaeota-Eocytes | `============ Eukaryotes The "eocyte tree": ,======== Eubacteria | | ,===== Euryarchaeota =====| | `==| ,== Crenarchaeota-Eocytes `==| `== Eukaryotes Domain Eukarya (includes Animals, Plants, Fungi, Protists, etc.)

The first and main characteristic of Eukarya (also called Eukaryotes) is that they have a nucleus and undergo mitotic division. They are also distinguished by complexity of their cells, which contain organelles that are usually membrane-bound. Some of the membrane bound organelles include the nucleus, chloroplasts, and mitochondria, among many others. Eukaryotes also have some organelles that are not membrane bound, such as motility devices (ex: flagella).

Domain Bacteria (ÒTrue Bacteria,Ó mitochondria, and chloroplasts) Bacteria are prokaryotes, which means they do not have a nucleus or membrane bound organelles. An example is cyanobacteria.

Domain Archaea (Halophiles, Methanogens, and their relatives) Archaea branched off from Bacteria very early in their evolutionary history. Both Archaea and Bacteria are prokaryotes that do not have a nucleus and internal organelles found in Eukaryotes. Even though the two came from the same origins, they are distinctly different. Archaea are more similar to Eukarya than Eubacteria, which means that it is more likely to be closely related to humans.

One of the kingdoms under Archaea is Crenarchaeota, which is very unique. The organisms in this kingdom can handle, even prefer extreme temperatures and acidity. These organisms are usually microscopic and single-celled, but they can live in environments that most other organisms would die in. Out of the species that are known, most of them come either from marine or terrestrial volcanic environments, such as shallow or deep-sea thermal vents and hot springs.

Kingdoms in the Domains: Domain: Bacteria Kingdom: Eubacteria Domain: Archaea Kingdom: Archaebacteria Domain: Eukarya Kingdoms: Protista, Plantae, Fungi, Animalia Lineage to classification of an organism: Domain Kingdom Phylum Class Order Family Genus Species

References:
Tree of Life http://phylogeny.arizona.edu/tree/life.html
Life The Science of Biology Fifth Edition. By William K. Purves, Gordon H. Orians, H. Craig Heller, and David Sadava. Published by Sinauer Associates, Inc. in 1998.

"Basic Information on the different environments in the ocean." One way of classifying organisms is by the lifestyle of the organism. Benthic organisms live on or are buried on the sea floor. Some organisms are sessile (attached to a substrate) and others can move around. Pelagic organisms live in the water column, away from the bottom. These organisms are further divided by how well they can swim. Organisms that swim weakly or not at all are plankton (they float with the currents). Planktonic algae and other autotrophs are called phytoplankton, which are the most important primary producers. The animal plankton is called zooplankton.

Animals that can swim well are called nekton. They are comprised mostly of vertebrates, mainly fish and mammals. However, there are some invertebrates that can swim on its own such as the squid and octopus.

Another way to classify marine organisms is by where they live.
The intertidal zone is the shallowest part of the shelf that is between land and sea. This area is where tides expose some of the shelf at times.
The subtidal zone is where benthic organisms live on the continental shelf beyond the intertidal zone.
The benthic zone is away from shelf, which is further divided into bathyal, abyssal, and hadal zones.
All three of these zones are considered the deep ocean (for simplicity).

However, the bathyal zone is where the shelf breaks (which means an increase in steepness that marks the outer edge of the continental shelf) and to a depth of approximately 4,000 meters (13,000 ft).
The abyssal zone is from the depths, of 4,000 m (13,000 ft) to 6,000 m (20,000 ft).
The hadal zone is below 6,000 m (20,000 ft). The pelagic zone refers to the continental shelf, and is also divided.
The area over the shelf is called the neritic zone.
The pelagic waters, beyond the area where the shelf breaks, are called the oceanic zone. The pelagic zone is divided vertically by depth as well as the amount of sunlight that each zone receives.
The shallowest level is the epipelagic zone, where there is plenty of sunlight for photosynthesis. This area extends to the depths of 100 m to 200 m (350 ft to 650 ft). Nearly all of the neritic waters lie in the epipelagic zone.
Next is the mesopelagic zone, where there is not enough light for photosynthesis but enough to see. This twilight zone is extends from 200m to 1,000 m (650 ft to 3,000 ft).

Lastly are the bathypelagic, abyssopelagic and hadopelagic zones, where no sunlight penetrates. This is called the deep-pelagic. These three zones have the same depth range as the three deep zones in the benthic section.

Animals in the intertidal zone deal with factors of changes in salinity, oxygen depletion, being exposed to predators, increase in temperature, wave actions, and most often desiccation. Therefore, most of the animals have a hard casing of some sort to help with all of these factors.

Animals in the pelagic zones, particularly in the upper column where sunlight still penetrates, have to deal with finding food, avoiding predators, and finding mates. Because these animals need to avoid predation, certain traits such as counter-shading and schooling, have evolved.

Lastly, organisms in the deep ocean deal with factors such as lack of food, mates, oxygen, and sunlight. Characteristics of these organisms are large, gaping mouths (to catch any size of prey), weak swimmers (do not want to use energy to swim), bioluminescence to find mates and food. Some deep ocean organisms lack eyes and others do not, they also use of pheromones to attract and find mates.

"Characteristics of Different Phyla"

Porifera
These animals are asymmetrical, meaning they have no symmetry. They are filter feeders by means of flagellated cells. Filter feeders pump in water so that they can obtain their food from what is in the water. In some cases, the exit ÔdoorÕ or osculum can been seen with the naked eye. Example: sponges.

Cnidaria
Cnidarians have medusa and polyp cycles. The medusa cycle is free swimming such as a jellyfish. The polyp cycle is stationary such as an anemone. They have radial symmetry with stinging cells called nematocysts. Examples: Jellyfish, hydroid, anemones and coral.

Platyhelminthes
There are unsegmented worms that are flattened dorsoventrally. They move by contracting muscles down its body (ungulates). They have bilateral symmetry with two eyespots, that are sometimes visible. Example: Flat worms such as the Mexican skirt dancer.

Annelida
They are segmented worms with bilateral symmetry. Each of their segments have a pair of parapodia for movement, which are ususlly visible to the naked eye. Examples: Fire worms and tube worms.

Arthropoda
These animals have bilateral symmetry and segmented bodies. They also have jointed appendages and an exoskeleton made of chiton. They have compound eyes, in which usually sit on stalks, such as a crab's eyes. Examples: crabs, shrimp, barnacles.

Mollusca
Mollusks have bilateral symmetry and a mantle. In snails, chitons, and bivalves, the mantle secretes their shell. In a squid, the mantle secretes a pen that is found within the squid. They also have a muscular foot to help with movement. In the cephalopods (octopus and squid), the foot has been modified into arms and tentacles. They also have a radula which is a feeding structure, much like a rough tongue.

Echinodermata
Echinoderms, which means spiny skin, have a calcarious exoskeleton with a water vascular system. A water vascular system is a network of water-filled canals that are used in locomotion and food-gathering. They have pentaradial symmetry. They move by their tube feet. They have capabilities of regeneration. Examples: Sea urchins, sea stars, sea cucumbers.

Chordata
Their characteristics are a notochord, hollow dorsal nerve chord, pharayngeal gill slits. Vertebrate chordates have a backbone. There are some chordates that do not have a backbone such as a tunicate. Examples: fish, sharks, humans, dogs, etc.

Reference: Marine Biology Third Edition By Peter Castro and Michael E. Huber. Published by McGraw-Hill Company in 2000.

Sample Dichotomous Key: Taking a penny, nickel, dime, and quarter as the ÒunknownÓ species, pick any coin to start with and begin at #1 and follow the steps. 1. Color a. It is silver in color (See #2) b. It is copper or brownish in color (Organism is a Penny) 2. Texture of edges a. Smooth (Organism is a Nickel) b. Rough (appear to have lines cut on the edges) (See #3) 3. Size a. Smaller than 2.0 cm (Organism is a Dime) b. Larger than 2.0 cm (Organism is a Quarter)

• Print out of activity from this lesson plan, if necessary.
• Dichotomous key Organisms (dead, alive, or pictures of at least 5 or more if available)
• Markers
• Clay
• Any art supplies that will be easy to manipulate for the making of the organism.
• Coins (pennies, nickels, dimes, quarters)
• Rulers

Engage: Identifying characteristics and possible habitats of organisms. Based on specific characteristics, describe why they might live in a particular habitat. Classification by phyla may be used with older students.

Preparation: This activity is meant to be an end to a comprehensive marine science unit. The students will need a basic knowledge of marine animals. For the set-up and take down of live organisms, they need to be placed in an enclosure with water during the activity. When the activity is finished, place the organisms back into the aquarium (live animals should not be out of their aquarium for extended periods of time). Preserved organisms, in their individual jars, should be placed on the tables. If using pictures, simply place them on the tables at the start of the activity and collect them at the end.

The activity that is included in this lesson plan, contains pictures of organisms as well as questions for the activity. Preparation, if using these pictures and questions, is to print the activity and make copies for the students. For the coin activity, the only preparation is obtaining the coins and printing off, or making your own, dichotomous key. The preparation for the activity of creating their own organism requires obtaining the supplies that are selected to be used (paper and markers, or clay) and then cleaning up at the end of the activity. See the following web-sites for additional information on how to build and use a dichotomous key. http://www.for.orst.edu/cof/teach/for241/dk/index.html http://www.ventura.cc.ca.us/depts/bio/marinebio/keying.htm http://pc65.frontier.osrhe.edu/hs/science/hbotkey.htm

Day 1: Place three or more organisms on a table per group. Students will write down all of the characteristics they see on each organism Students will give a possible location of habitat. Students will give the organism an over all name (a phylum name for the older students). In preparation for the next activity, introduce a dichotomous key by the use of coins. For information on how to accomplish this, look at the second web site listed under preparation, as well as a sample key included in the background information.

Day 2: Take a dichotomous key and the same organisms, from the previous day, and follow it to identify the organisms previously characterized.

Day 3: Following the example of the coin dichotomous key, have the students make their own dichotomous key using something that is of interest to the students (i.e. shoes, Pokemon cards, candy, etc.).

Day 4: Have students create, name, and place their own organism in a group and habitat. After the creation of the organism, the students will exchange their organism and discuss it with each other.