Question

Biology Lab
Classification and Dichotomous Key...

Answer 1

Okay, so question #1 asks us what a "classification key" is.

You're on the right track there.

A classification key, like the Dichotomous key that you used, is a way of grouping organisms, based on their appearance.

Answer 2

Question #2 asks us for four different characteristics that were used in the shark key.

In other words,
we have to come up with four ways to tell sharks apart, based on the key.

There were a handful, but we only have to choose four.

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You've got 2 of them so far...

1. Shape of shark
2. Size of shark


You started on the third characteristic with "present..."

You could say "Presence of pelvic fin."

Because some of the sharks have a pelvic fin, and some don't.

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As for a fourth characteristic, you can see that some sharks have a NEEDLE-POINT NOSE,
and some don't.

So, you can say "presence/absence of needle-point nose."

It's one more way of telling sharks apart.

Answer 3

Take a look at question #3.

Shark #4 and shark #8 look almost alike.

They're different in size, you're right.

But I'm also looking at something else.
I'm looking at a certain body part: the ANAL FIN.

Shark #4 has an anal fin,
but shark #8 doesn't.

Answer 4

And for question #4,

We have to tell the biggest difference between shark #4 and shark #7.

Take a look at both of their CAUDAL fins.
Note the difference.

Now, take a look at #9 on your KEY LIST.
It talks about CAUDAL FINS.

~~~~~~~~~~

Let's look at shark #4.

The top and the bottom halves of its CAUDAL FIN are UNEVEN, you see?


Now, look at shark #7.

I'm looking at its caudal fin,
and I see that the top and the bottom halves are both EVEN.
They're both the same size.

Answer 5

for four can i also put dorsal fin?

Answer 6

And i need help in making the dichotomous key

Answer 7

i dont get how to make it..

Answer 8

Shark #4 and shark #7 have more or less the same dorsal fin, the way I see it.

Answer 9

ok so its the caudal fin

Answer 10

Shark #4 and shark #7 have more or less the same dorsal fin, the way I see it.

You only need one distinction. I'd go with their caudal fins.

Answer 11

alright....help with making the key..

Answer 12

I'm looking at fish #5.

The one thing that sets it off from all the other fish is the black spot on its body.

Answer 13

I'm looking at fish #2,

and it doesn't have any pelvic fins.

Answer 14

The difference between fish #3 and #4
is that fish #3 has a jagged-edge dorsal fin.

Fish #4 has a smooth-edge dorsal fin.

Answer 15

ok so please show me exactly how to set it up the dichotomous key

Answer 16

Is this enough to help you get started?

#1 has already been given to us:

~~~~~~~~~

1. Tube like body = Sandvigidae
Non-tube like body = go to statement 2.

Answer 17

but i dont get what to put next for 2a and 2b and so on

Answer 18

This is how we use the dichotomous key:

First, we pick a fish.

Then, we put it through all of the statements, in order,
until we reach a statement that can describe the fish.

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Answer 19

ok so this is what i put: 2a. A fish with one dorsal fin Got to statement 3
2b. A fish with two dorsal fin Family Karnisdae..????

Answer 20

Look at fish #5.

The one thing that sets it apart from all the other fish is that it has a black spot, on its body.

So, we can set up #2 like this:

2. Black spot on body = Dohertyidae
No black spot on body = go to statement 3.

Answer 21

ohhh

Answer 22

Your way could also work,
because I see that fish #2 is the only fish with 2 dorsal fins.

There's more than one way to do this.

Answer 23

wait im doing it your way.....help me with statement 3

Answer 24

I noticed that fish #2 is the only fish with a pointed dorsal fin.

Answer 25

yeah maybe that can do in statement 3

Answer 26

so what should i put for 3?

Answer 27

You can do that.

Answer 28

3. Pointed dorsal fin = Karnsidae
Non-pointed dorsal fin = go to statement 4

Answer 29

Pointed dorsal fin Family Karnsidae
Non po

Answer 30

oh thats exactly what i was going to put

Answer 31

Yes.

Now, the only two fish left are what? #3 and #4?

Answer 32

Fish #3 has a jagged-edge dorsal fin.
Fish #4 has a smooth edge dorsal fin.

Answer 33

So, we can set up statement 4 like this:

4. Jagged-edge dorsal fin = Ramirezidae
Smooth-edge dorsal fin = Lundbergidae

Answer 34

jagged edge and smooth edge? how can u tell?

Answer 35

Look at their dorsal fins. Both #3 and #4.

#3 has a dorsal fin that has a sort of zig-zag edge.

#4's dorsal fin looks a lot curvier.

Answer 36

oh..

Answer 37

The "dorsal" fin is the fin on its back. The top fin. You know.

Answer 38

Other than that, I can't see anymore differences between fish #3 and #4.

#3 does seem to have darker-colored fins, but I'm not sure how I'd describe that.

Answer 39

Besides, it's not the only one with dark fins.

Answer 40

wait cant the jagged and smooth edge go last cux their bothe familys

Answer 41

like for statement 5

Answer 42

Statement 4 is the last statement we really need to fill in.

Answer 43

oh so we dont have to fill in statement 5

Answer 44

It's optional to fill them all in.

As long as we've covered all the fish, I think we should be okay.

Answer 45

oh ok yeah i remember the teacher saying something like that...

Answer 46

Okay. You're set. Good job.

Answer 47

Ok thanks!!!

Answer 48

I really appreciated ur help

Answer 49

Oh yeah, no problem.