Dichotomous Key & Matching Answers

-Dichotomous Key-
1)annelida-10b
2)arthropoda-9b
3)mollusca-11a
4)platyhelminthes-9a
5)echinodermata-10a
6)nematoda-11b
7)cnidaria-8b
8)porifera-8a

-Matching-
1.g
2.e
3.c
4.d
5.a
6.f
7.h
8.b

Matching

____1.Invertebrates with radial symmetry that evolved from animals with bilateral symmetry.
____2. Invertebrates with radial symmetry and no true circulatory system.

____3. Invertibrates with exoskeletons

____4. Segmented worms

____5.Flatworms

____6. Roundworms

____7. Invertebrates with shells, generally aquatic.

____8.Simplest adn oldest of all invertebrates

a. platyhelminthes
b. porifera
c. arthropoda
d. annelida
e. cnidaria
f. nematoda
g. echinodermata
h.mollusca

Dichotomous key pictures

Dichotomous Key

1) a. has symmetry -go to- 2
b. no symmetry -go to- 8

2) a. radial symmetry -go to- 3
b. bilateral symmetry -go to- 4

3) a.have no true skeleton -go to- 8
b.ahve mesodermal endoskeleton -go to-10

4) a. segmented -go to- 5
b. unsegmented -go to- 6

5) a. exoskeleton -go to- 9
b. lack of hard skeleton -go to-10

6) a. has a shellor beak -go to-11
b. lack of shell or beak -go-to- 7

7) a. one body opening -go-to- 9
b. two body openings -go-to-11

8) a. Porifera
b. Cnidaria

9) a. Platyhelminthes
b. Arthropoda

10) a.Echinodermata
b. Annelida

11) a.Mollusca
b. Nematoda

Introduction to Invertibrates

Invertebrates, or animals without a backbone, make up over 95% of all animals on earth. They range from creatures that make their home in the deep blue sea, like sea anemones and jellyfish, to more shallow water organisms such as coral. Other invertebrates can walk on land such as spiders and crabs, and yet others can fly like butterflies, dragonflies, and bees. Invertebrates also range from very simple organisms, such as worms, sponges, and starfish, to very complex organisms such as octopodes.

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Pictures of some

invertebrates

leech

crab






caterpillar

squid

jellyfish






snail






spider








worm








fly







bee






sand dollar







dragonfly








oyster







sea cucumber







coral










clam







sponge







starfish









shrimp







scorpion







octopus

Arthropoda

There are many animals in the phylum anthropoda, some of which are crabs, spiders, caterpillars, butterflies, scorpions, and bees; basically insects, spiders and crustaceans (animals that have a hard outer shell and no bones inside them also known as an exo-skeleton.) Two examples of these animals are crabs and beetles. Arthropods have a segmented body with appendages (arms or legs) on each segment. Arthropods have bilateral symmetry, which means that they can be divided one way into two halves that look the same. Like the trapezoid and the scorpion shown below. Arthropods have two body openings, one at their head, one at the other end of their body at the end of the abdomen. Arthropods have a much simpler nervous system than humans, basically they have two nerves that go along the body, and have nerves branching off. The two main nerves fuse in the head to form a brain. Arthropods reproduce with eggs that the female lays and the males fertilize. Arthropods do not have a true circulatory system. They do not have viens or arteries, instead they have an copper based, oxygen carrying protein in their "blood", as opposed to humans who have iorn based hemoglobin to transpoer oxygen. Their "Blood" in pumped by many hearts, into the body cavity where it oxygenates the tissues.
Arthropods breathe in many different ways. Arthropods that live mainly in water have gills specialized for gas exchange in water. Arthropods that are terrestrial, or live on land, have internal surfaces to process oxygen, such as lungs. Some arthropods have an oxygen-absorbing membrane to help them obtain oxygen. Arthropoda is the largest phylum of animals in the animal kingdom.

Echinodermata

The phylum Echinodermata includes animals such as starfish, sea cucumbers, sea urchans, and sand dollars. Ecdhinnoderms are marine animals which means that they live in water. Echinoderms evolved from animals with bilateral symmetry into marine animals with radial symmetry.
All echinoderms have fivefold radial symmetry
at one piont in their life. They also have an endoskeleton, inner

support system, which most invertibrates do not have.
Echinoderms have one body opening that serves as both a

mouth and anus.They have a radial nervous system,which is basically a "net"or "web" of nerves centralized around the body opening and branches our into the appendages. Echinoderms don't have a brain. Echinoderms reproduce sexually with external fertlization, they do this by releasing sperm and egg into the water and the eggs get fertilized. Some echinoderms have the ability to regenerate limbs, in the case of the starfish, it can regenerate it self from one limb so long as there is some of the body of the starfish still attached. Echinoderms have an open circulatory system. There are no blood vessels present, the blood mixes freely with other body fluids and is pumped by a series of hearts. A hydraulic water vascular system aids Echinoderms in movement, circulation and "breathing," or more accurately, gas exchange.

Mullosca

Organisms belonging to the phylum Mollusca include: shelfish(clams, oysters), snails, octopodes, and squid. The phylum mullosca is filled with a diverse group of animals, mostly aquatic. Molluscs have blateral symmetry and contain some of the most complex invertebrates such as octopodes. Most molluscs have two body opening used for both eating and expelling waste. some more complex organisms such as ocoopodes and squid have brains and a more human-like nervous system, but most molluscs have no brain and just nerves that controll movement. molluscs have gills to help them excange gasses under water.

molluscs have a relatively simple circulatory system that consists of hearts and "blood. the phylum Mollusca is one of the most diverse groups of invertibrates.

Annelida

Annelids are the segmented worms, their body is divided into many segments which affects many of their basic functions. probably the most common annelid is the earthworm, found almost everywhere on land. Annelids have bilateral symmetry, and two body openings. Annelids can live on land or in water. The circulatory and nervous system work together in annelids the blood is carried in a blood vessel and conected to the nervous system. Annelids can reproduce by regenerating pieces of themselves that break off into new worms, or they can reproduce sexually either with seperate sexes or hermaphroditicly, both worms have both male and female organs, and both become fertilized.

Nematoda

Nematodes are the round worms, that can be either parasidic or free-living, and live in great abundence in almost every place on earth. Nematodes have bilateral symmetry . Nematodes have no circulatory or respiratory systens so the use diffusion, the movement of matter, in this case gases, from and area or higher concentration to and area of lower concentration without the use of energy. Nematodes generally reproduce sexually, and produce eggs, the eccs hatch into larva which eventually become mature nematodes. A nematode's nervous system consists of two main nerves running paralell to the body of the worm with smaller nerves branching off.

platyhelminthes

Platyhelminthes are flatworms. they have bilateral symmetry. most have only one body opening if that. they can be parasidic or free living. Platyhelminthes reproduce sexually. They are hermaphoditic, which means they have both male and female sex organs and when they repeoduce they both become fertilized. they do not have a true circulatory or respiratry system, they exchange gasses through diffusion.

Cnidaria

Cnidarians are animals with radial symmetry and live in water. Some of these animals move, some do not. Cnidarians are some of the simplest organisms found in the water.Cnidarians include animals such as sea anemones (that's what nemo lived in), jellyfish, and coral.
cnidarians have radial symmetry, they have more than one line where they can be divided into two equal halves, like the pie shown below.Cnidarians have one body opening, the gastrovascular cavity, is used a cnidarians as both a mouth and an anus. Like many simpler organisms, cnidarians do not have a circulatory system or respiratory, instead they exchange

gasses by diffusion. Cnidarians have a netlike nervous system, with nerves all around the mouth and branching to the rest of the organism. Cnidarians reproduce asexually by budding, and sexually when the male sperm and the female egg are released into the water and unite to become a fertilized zygote.

Porifera

Porifera is a phylum of invertebrates containing sponges. Sponges are the simplest as well as the oldest of all of the invertebrates.Sponges have no symmetry, in other words, there is no line that can be drawn on a sponge to divide it into two mirrored halves. Sponges do not have body openings, instead they have pores that function for obtaining nutrients and they use water to propel waste away from them. Sponges reproduce asexually by budding, and sexually bu releasing sperm and eggs into the water and having the eggs get fertilized. When budding occurs, a smaller sponge begins to grow on the parent sponge. Sponge also have a great abilito to regenerate, if a piece of a sponge breaks off it can become a new sponge. Sponges do not have a true circulatory system, instead they filter water through their bodies and obtain oxygen by diffusion, the movement of some form of matter from an area of high concentration to an area of lower concentration.





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