Echinoderm

Echinoderms

All Materials © Cmassengale

Phylum Echinodermata
Characteristics

All marine
Known as spiny-skinned animals
Endoskeleton known as the test is made of calcium plates or ossicles with protruding spines
Includes sea stars, brittle stars, sand dollars, sea urchins, & sea cucumbers
Undergo metamorphosis from bilateral, free-swimming larva to sessile or sedentary adult
Larval stage known as dipleurula or bipinnaria
Adults have pentaradial ( 5 part) symmetry
Lack segmentation or metamerism
Coelomate
Breathe through skin gills as adults
Capable of extensive regeneration

Bipinnaria Larva

Ventral (lower) surface called the oral surface & where mouth is located
Dorsal (upper) surface known as aboral surface & where anus is located
Have a nervous system but no head or brain in adults
No circulatory, respiratory, or excretory systems
Have a network of water-filled canals called the water vascular system to help move & feed
Tube feet on the underside of arms help in moving & feeding
One-way digestive system consists of mouth with oral spines, gut, & anus
Deuterostomes (blastopore becomes the anus)
Separate sexes
Reproduce sexually & asexually
Includes 5 classes:
* Crinoidea – sea lilies & feather stars
* Asteriodea – starfish
* Ophiuroidea – basket stars & brittle stars
* Echinoidea – sea urchins & sand dollars
* Holothuroidea – sea cucumbers

Class Crinoidea
Characteristics

Sessile
Sea lilies & feather stars

FEATHER STAR

SEA LILY

Have a long stalk with branching arms that attach them to rocks & the ocean bottom
Can detach & move around
Mouth & anus on upper surface
May have 5 to 200 arms with sticky tube feet to help capture food (filter feeders) & take in oxygen
Common in areas with strong currents & usually nocturnal feeders

Class Asteroidea
Characteristics

Usually sedentary along shorelines
Starfish or sea stars
Come in a variety of colors
Prey on bivalve mollusks such as clams & oysters

Starfish Feeding on Clam

Have 5 arms that can be regenerated
Arms project from the central disk
Mouth on oral surface (underside)

STARFISH

Class Ophiuroidea
Characteristics

Largest class of echinoderms
Includes basket stars & brittle stars

BASKET STAR

BRITTLE STAR

Live on the ocean bottom beneath stones, in crevices, or in holes
Have long, narrow arms resembling a tangle of snakes
Arms readily break off & regenerate
Move quicker than starfish
Feed by raking in food with arms or trapping it with its tube feet

Class Echinoidea
Characteristics

Includes sea urchins & sand dollars

SEA URCHIN

SAND DOLLAR

Internal organs enclosed by endoskeleton or test made of fused skeletal plates
Body shaped like a sphere (sea urchin) or a flattened disk (sand dollar)
Lack arms
Bodies covered with movable spines
Have a jawlike, crushing structure called Aristotle’s lantern to grind food
Use tube feet to move
Sea Urchins:
* Spherical shape
* Live on ocean bottom
* Scrape algae to feed
* Long, barbed spines make venom for protection
Sand Dollars:
* Flattened body
* Live in sand along coastlines
* Shallow burrowers
* Have short spines

Class Holothuroidea
Characteristics

Includes sea cucumber

SEA CUCUMBER

Lack arms
Shaped like a pickle or cucumber
Live on ocean bottoms hiding in caves during the day
Have a soft body with a tough, leathery outer skin
Five rows of tube feet run lengthwise on the aboral (top) surface of the body
Have a fringe of tentacles (modified tube feet) surrounding the mouth to sweep in food & water
Tentacles have sticky ends to collect plankton
Show bilateral symmetry
Can eject parts of their internal organs (evisceration) to scare predators; regenerate these structures in days

Structure & Function of Starfish
Body Plan

Range in size from 1 centimeter to 1 meter
Mouth located on oral surface (underside)
Have an endoskeleton made of calcium plates
Sharp, protective spines made of calcium plates called ossicles found under the skin on the aboral (top) surface

ABORAL SURFACE

Have pedicellariae or tiny, forcep-like structures surrounding their spines to help clean the body surface

Water Vascular System

Network of canals creating hydrostatic pressure to help the starfish move

WATER VASCULAR SYSTEM

Water enters through sieve plate or madreporite on aboral surface into a short, straight stone canal
Stone canal connects to a circular canal around the mouth called the ring canal
Five radial canals extend down each arm & are connected to the ring canal
Radial canals carry water to hundreds of paired tube feet

TUBE FEET

Bulb-like sacs or ampulla on the upper end of each tube foot contract & create suction to help move, attach, or open bivalves
Rows of tube feet on oral surface (underside) are found in ambulcaral grooves under each arm

Tube Feet in Ambulcaral Grooves

Feeding & Digestion

Tube feet attach to bivalve mollusk shells & create suction to pull valves apart slightly
Starfish everts (turns inside out) its stomach through its mouth & inserts it into prey
Stomach secretes enzymes to partially digest bivalve then stomach withdrawn & digestion completed inside starfish

Other Body Systems

No circulatory, excretory, or respiratory systems
Coelomic fluid bathes organs & distributes food & oxygen
Gas exchange occurs through skin gills & diffusion into the tube feet
No head or brain
Have a nerve ring surrounding the mouth that branch into nerve cords down each arm
Eyespots on the tips of each arm detect light
Tube feet respond to touch

Reproduction

Separate sexes
Two gonads (ovaries or testes) in each arm produce eggs or sperm
Have external fertilization
Females produce up to 200,000,000 eggs per season
Fertilized eggs hatch into bipinnaria larva which settles to the bottom after 2 years & changes into adult
Asexually reproduce by regenerating arms

BACK

Echinoderm Study Guide

Know the answers to the following:

A water vascular system is a trait of?

Clams are the basic food for what echinoderm?

A sea star feeds by extending what?

A sea star’s endoskeleton is made of what type of plates?

What around the mouth of a starfish helps coordinate its movements?

Tube feet are part of what echinoderm system?

The blastopore becomes the anus in what type of organism?

Are chordates & echinoderms protostomes or deuterostomes?

Echinoderms like the sea urchin have what type of symmetry?

Are echinoderms fast or slow moving organisms?

How do echinoderms move?

Echinoderm larva have what type of symmetry?

What are the muscular sacs that force water through the water vascular system called?

In what phylum are sea squirts or tunicates?

Tunicates have a leathery what?

What animals are in the class Ophiuroidea?

How do basket stars & brittle stars differ?

What is the purpose of spines on a brittle stars arms?

Name an adult echinoderm with bilateral symmetry.

Do humans have a tail at any point during their development?

What was the function of gill slits in early chordates?

What is the flexible tube below the nerve cord in chordates called?

Where are lancelets usually found?

Be able to label the parts of the water vascular system of a starfish.

Notes

Study Guides

Ecology

Ecology

All Materials © Cmassengale

Ecology is the study of interactions between organisms (biotic part) and their nonliving environment (abiotic factors)

Biotic factors includes plants, animals, fungi, & microorganisms. They may be producers, consumers, or decomposers.

Abiotic factors include climate, soil, temperature, water, air, sunlight, humidity, pH, and atmospheric gases.

Habitat is the place a plant or animal lives, while its niche is its total way of life.

Life is organized into levels:

Organism (any single living thing)

Population (members of the same species living in one place)

Community (all the populations living in an area)

Ecosystem (community living in a similar habitat such as a forest)

Biomes (ecosystems covering wide areas & with similar climates & organisms)

Biosphere ( all the living & nonliving things on earth)

Producers:

	Make their own food through photosynthesis or chemosynthesis
	Includes plants, algal protists, & some bacteria

Consumers:

	Can’t make their own food
	May be herbivores (feed only on plants), carnivores (feed only on animals), or omnivores (feed on plants & animals)

Decomposers:

	Break down dead plants & animals (detritus)
	Recycle nutrients
	Called detritivores
	Include fungi & bacteria

Sunlight is the ultimate energy for all life on earth, but only producers can get their energy directly from the sun.

Energyflowinecosystemimage

Trophic levels are feeding levels of producers & consumers in an ecosystem:

	1st Trophic Level is producers that use sunlight directly
	2nd Trophic Level includes herbivores that feed directly on plants
	Higher Trophic Levels are carnivores feeding on each other

energypyramid

Food chains & food webs:

	Chains show who eats whom in an ecosystem.
	Webs are made up of several food chains.
	Always begin with producers absorbing sunlight.
	Producers store energy in the chemical bonds of the food they make.
	Stored energy is passed to consumers when they eat producers or other consumers.
	Some energy is lost at each trophic level as heat when consumers “burn” food during cellular respiration.
	Both energy & nutrients must move through an ecosystem.

Three main elements that must move through an ecosystem:

	Water
	Carbon
	Nitrogen

Water or Hydrologic Cycle:

	Cells are 70 – 90% water
	Water is needed for metabolic processes
	Water is most important for terrestrial organisms because of desiccation (drying out)

Steps in the water Cycle:

Evaporation Transpiration
(water loss from lakes, rivers, oceans…) (water loss from plant leaves)

¯ ¯

Condensation
(water vapor forms clouds)

Precipitation
(water returns to earth as sleet, rain, snow…)

Surface Runoff
(returns water to bodies of water or to groundwater)

Carbon Cycle:

	Consists of photosynthesis, cellular respiration, & decomposition
	Begins with producers taking carbon dioxide from the air during photosynthesis
	Carbon dioxide used in cellular respiration
	Decomposing plants and animals return Carbon to the soil

Carbon Cycle Steps:

Plant leaves take carbon dioxide from air

Plants store carbon in carbohydrates or starches
(photosynthesis)

Plants & animals release carbon dioxide back into the air
(cellular respiration)

Decomposers return carbon to environment
(decomposition)

Nitrogen:

	Needed by all organisms
	Used to make proteins & nucleic acids (DNA & RNA)
	Air made up of 80% nitrogen
	Only Cyanobacteria & Rhizobium bacteria can use nitrogen directly from the air (nitrogen fixation)
	Bacteria found in the soil & on the roots of legumes (beans, peas …)

Steps in the Nitrogen Cycle:

Cyanobacteria & Rhizobium take nitrogen from air
(nitrogen fixation)

Convert nitrogen gas into ammonia

Nitrifying bacteria in soil change ammonia into nitrates

Plants can absorb & use nitrates to make proteins

Consumers eat plants & get proteins containing nitrogen

Decomposers break down dead organisms & return nitrogen to air
(called ammonification)

Anaerobic bacteria in soil release nitrogen from nitrates into air
(called denitrification)

Three main types of ecosystems:

	Terrestrial (land)
	Freshwater (rivers, ponds, lakes …)
	Marine (oceans & seas)

Terrestrial ecosystems are divided into 7 biomes with similar climates & organisms

Seven Terrestrial Biomes:

	Tropical Rain Forest (jungle)
	Savanna (tropical grasslands)
	Deserts
	Grasslands
	Deciduous Forest
	Taiga (coniferous forest)
	Tundra

Tundra:

	Cold & dark most of the year
	Includes the arctic
	Permafrost is the top layer of soil that thaws & in which plants grow
	No trees, but sedges & grass, mosses, & lichens
	Many migratory animals
	Lemmings & ptarmigans are year round residents
	Approximately 20 cm annual rainfall

Tundra

Taiga:

Coniferous forest
Extends across northern Eurasia & North America
Contains conifers or evergreens (spruce, cedar, fir, pine …)
Needle like leaves withstand weight of snow
Bear, deer, moose, wolves, mountain lions …
Sequoia or redwood (largest conifer) grows here
Bristle cone pine oldest living conifer found here

Coniferous Forest

Temperate Deciduous Forest:

South of taiga in North America, eastern Asia, & Europe
High annual rainfall (75-150 cm)
Moderate temperatures
Well-defined seasons of about equal length
Trees loose leaves in winter (deciduous)
Show stratification (plant layers):
1. Canopy – broad leaf deciduous trees forming uppermost layer
2. Under story – shrubs
3. Forest Floor – herbaceous plants
Songbirds, deer, rabbits, foxes, squirrels, frogs 7 toads, lizards …

Temperate Deciduous Forest

Tropical Rain forest:

Near equator
Warm climate (20 -25 degrees C)
Plentiful rainfall (190 cm/year)
Contains the greatest diversity of plants & animals
Insects, monkeys & apes, snakes, tropical birds, leopards…
Animals & plants brightly colored
Poor soil for agriculture

Rainforest

Grasslands:

Mostly grasses with a few trees due to less rainfall
Moderate climates
Good for agricultural crops
Grazing & burrowing animals dominate
Also called prairies

Grassland

Savanna:

Tropical grasslands
Warm climate & rainy season
Antelope, zebra, lions, wildebeests, hyenas, elephants…
Suffer from floods & drought

(26KB)

Deserts:

Low annual rainfall
Subject to strong winds
Days usually hot & nights cold
Sahara desert is without vegetation
Succulents such as cacti & other water storing plants
Most animals nocturnal
Lizards, snakes, roadrunners, insects, tarantula, hawks, rodents, coyotes…

Desert

Aquatic Biomes:

May be freshwater or saltwater
Wetlands near oceans have brackish water (mixture of fresh & salt waters)
Part of the part water or hydrologic cycle
Often polluted by man’s activities

Lakes & Rivers:

Freshwater
Oligotrophic lakes are nutrient poor (catfish, carp…)
Eutrophic lake are nutrient rich (trout, bass…)
Deep lakes have layers or strata where different plants & animals live
Phototropic organisms in upper layers for light
Estuary at mouth of river contains brackish water

Ocean Zones:

Intertidal zone
1. Along shoreline
2. Wave action
3. Lots of light so many producers
4. Starfish, sand dollars…
Neritic Zone
1. Ocean water above continental shelf
2. Coral reef found here
3. Surrounds continents & receives light in upper layers
Oceanic Zone
1. Beyond continental shelf
2. Deepest area (up to 7 miles)
3. Bottom doesn’t receive light so animals adapted to darkness (many produce their own light, feed on other animals…)
4. Deepest area called abyss
5. Upper area gets light & called the photic zone (lots of seaweed here)
6. Floaters called plankton (microscopic organisms)
7. Swimmers such as fish called nekton
8. Bottom dwellers called benthos

BACK

Ecology Study Guide

Ecology Study Guide

List several biotic factors in an ecosystem.

List several abiotic factors in an ecosystem.

What serves as the ultimate energy for all life on earth?

What is transpiration & what cycle is it a part of ?

Why are the Rhizobium bacteria beneficial to plants?

What is nitrogen fixation?

What is denitrification?

Where is the intertidal zone found & list several organisms that would be found there?

Name 3 types of consumers based on their eating habits.

What is detritus & why is it important?

What are trophic levels & give an example?

What is the term for an organism’s total way of life?

How does an animal’s habitat differ from its niche?

Compare & contrast biomes.

Describe estuaries.

How does an oligotrophic lake differ from a eutrophic lake?

What is brackish water & where would it be found?

Where is the neritic zone found & what organisms would be found there?

Where would benthos organisms be found? Give an example of such a dweller.

Describe abiotic & biotic factors for each of these biomes:

Tropical rain forest

Taiga

Tundra

Grassland

Savanna

Desert

Deciduous forest

Intertidal Zone

Neritic Zone

Oceanic Zone

Oligotrophic River

Eutrophic River

Estuary

BACK

Introduction to Dichotomous Key Maker:

The identification of biological organisms can be greatly simplified using tools such as dichotomous keys. A dichotomous key maker is an organized set of couplets of mutually exclusive characteristics of biological organisms. You simply compare the characteristics of an unknown organism against an appropriate dichotomous key. These keys will begin with general characteristics and lead to couplets indicating progressively specific characteristics. If the organism falls into one category, you go to the next indicated couplet. By following the key and making the correct choices, you should be able to identify your specimen to the indicated taxonomic level.

Couplets can be organized in several forms. The couplets can be presented using numbers (numeric) or using letters (alphabetical). The couplets can be presented together or grouped by relationships. There is no apparent uniformity in presentation for dichotomous keys.

Sample keys to some common beans used in the kitchen:

Numeric key with couplets presented together. The major advantage of this method of presentation is that both characteristics in a couple can be evaluated and compared very easily.

1a.	Bean round	Garbanzo bean
1b.	Bean elliptical or oblong	Go to 2

2a.	Bean white	White northern
2b.	Bean has dark pigments	Go to 3

3a.	Bean evenly pigmented	Go to 4
3b.	Bean pigmentation mottled	Pinto bean

4a.	Bean black	Black bean
4b.	Bean reddish-brown	Kidney bean

Alphabetical key with couplets grouped by relationship. This key uses the same couplet choices as the key above. The choices within the first and succeeding couplets are separated to preserve the relationships between the characteristics.

A.	Bean elliptical or oblong	Go to B
	B. Bean has dark pigments	Go to C
	C. Bean color is solid	Go to D
	C. Bean color is mottled	Pinto bean
	D. Bean is black	Black bean
	D. Bean is reddish-brown	Kidney bean
	B. Bean is white	White northern
A.	Bean is round	Garbanzo bean

Rules for Using Dichotomous Keys:

When you follow a dichotomous key, your task becomes simpler if you adhere to a few simple rules of thumb:

Read both choices in a couplet carefully. Although the first description may seem to fit your sample, the second may apply even better.
Keep notes telling what sequence of identification steps you took. This will allow you to double-check your work later and indicate sources of mistakes, if they have been made.
If you are unsure of which choice to make in a couplet, follow both forks (one at a time). After working through a couple of more couplets, it may become apparent that one fork does not fit your sample at all.
Work with more than one sample if at all possible. This will allow you to tell whether the one you are looking at is typical or atypical. This is especially true when working with plants – examine more than one leaf, branch, cone, seed, flower,…etc.
When you have keyed out an organism, do not take your effort as the final result. Double check your identification scheme, using your notes. Find a type specimen (if available) and compare your unknown to the type specimen. If a type specimen is unavailable, find a good description of the indicated taxonomic group and see if your unknown reflects this description.
When reading a couplet, make sure you understand all of the terms used. The best keys will have a glossary of technical terms used in the key. If a glossary is unavailable, find a good reference work for the field (textbook, biological dictionary,…etc.) to help you understand the term.
When a measurement is indicated, make sure that you take the measurement using a calibrated scale. Do not “eyeball” it or take a guess.

Exercise 1:

Using a container of beans, use one of the dichotomous keys above to identify the beans. Glue the beans to the card provided and label them with their common name. Indicate what steps you followed to arrive at your answer. Turn the card in to your instructor. Compare your answers to the instructor’s descriptions and type specimen.

Exercise 2:

Obtain samples of the snack chips provided. Develop a dichotomous key to identify the snacks. In your notebook, keep track of the characteristics you used to differentiate between the different snack families. What are the values of the characteristic for each snack food?

Exercise 3:

Use the dichotomous key to conifers provided below to identify conifers.

A Key to Selected North American Native and Introduced Conifers

01a	Leaves needle-like	Go to 02
01b	Leaves flattened and scale-like	Go to 27

02a	Leaves are in clusters	Go to 03
02b	Leaves are borne singly	Go to 15

03a	Two to five leaves in a cluster	Go to 04 Genus Pinus
03b	More than five leaves in a cluster	Go to 14

04a	Leaves mostly 5 in a cluster	White Pine (Pinus strobus)
04b	Leaves 2 or 3 in a cluster	Go to 05

05a	Leaves mostly 3 in a cluster	Go to 06
05b	Leaves mostly 2 in a cluster	Go to 08

06a	Leaves twisted, less than 5 inches long	Pitch Pine (Pinus rigida)
06b	Leaves straight, more than 5 inches long	Go to 07

07a	Leaves 5-10 inches long, cones very thorny	Loblolly pine (Pinus taeda)
07b	Leaves mostly over 10 inches long, cones unthorned	Longleaf pine (Pinus palustris)

08a	Leaves mostly longer than 3 inches	Go to 09
08b	Leaves mostly shorter than 3 inches	Go to 11

09a	Leaves rigid, bark grayish	Black pine (Pinus nigra)
09b	Leaves narrower than 1.6mm; bark reddish brown or brown	Go to 10

10a	Cones thornless, twigs brown	Norway pine (Pinus resinosa)
10b	Cones thorny, twigs whitish	Shortleaf pine (Pinus echinata)

11a	Leaves mostly wider than 1.5 mm	Go to 12
11b	Leaves mostly narrower than 1.5 mm	Go to 13

12a	Leaves mostly longer than 35 mm	Mugho pine (Pinus mugo)
12b	Leaves mostly shorter than 35 mm	Jack pine (Pinus banksiana)

13a	Twigs whitened	Virginia pine (Pinus virginiana)
13b	Twigs not whitened	Scotch pine (Pinus sylvestris)

14a	Leaves deciduous, clusters of 20-40	Larch (Larix sp.)
14b	Leaves persistent, stiff, and four sided	True cedar (Cedrus sp.)

15a	Needles short and sharp	Giant Sequioa (Sequioadendron giganteum)
15b	Needles longer than 12 mm	Go to 16

16a	Tiny pegs on twigs	Go to 17
16b	No pegs on twigs	Go to 22

17a	Pegs square, needles sharp	Go to 18 Genus Picea
17b	Pegs round, needles flat and blunt	Hemlock (Tsuga sp.)

18a	Leaves dark green or yellow green	Go to 19
18b	Leaves blue-green	Go to 20

19a	Branchlets droop	Norway spruce (Picea abies)
19b	Branchlets do not droop	Red spruce (Picea rubens)

20a	Leaves at right angles to stems	Blue spruce (Picea pungens)
20b	Leaves point forward	Go to 21

21a	Leaves about 12 mm long, seed cones 15-32 mm in length, crown narrow and pointed	Black spruce (Picea mariana)
21b	Leaves about 19 mm long, seed cones 50 mm in length, spire-like crown	White spruce (Picea glauca)

22a	Buds large and pointed	Douglas fir (Pseudotsuga sp.)
22b	Buds small and rounded	Go to 23

23a	Terminal buds round and clustered	True fir (Abies sp.)
23b	Terminal buds not clustered	Go to 24

24a	Needles white underneath	Go to 25
24b	Needles green underneath	Go to 26 Genus Taxus

25a	Needles pointed	Redwood (Sequoia sempervirens)
25b	Needles blunt	Hemlock (Tsuga sp.)

26a	Leaves 18 mm long or less with inconspicuous midrib	American Yew (Taxus canadensis)
26b	Leaves 25 mm long or more with conspicuous midrib	Japanese Yew (Taxus cuspidata)

27a	All leaves short and sharp	Giant Sequioa (Sequioadendron giganteum)
27b	Some leaves not sharp	Go to 28

28a	Cones round	Go to 29
28b	Cones not round	Go to 31

29a	Cones soft and leathery	Juniper (Juniperus sp.)
29b	Cones woody	Go to 30

30a	Cones under 12 mm in diameter	False cypress (Chamaecyparis)
30b	Cones over 12 mm in diameter	Cypress (Cuppressus)

31a	Cones resemble rosebuds	White cedar or arbor vitae (Thuja)
31b	Cones resemble duck bills	Incense cedar (Calocedrus)