Marine Biology Questions

[Joel Seay]

I have two questions I need to know for an upcoming test. The answers are no
where to be found in my book and I don't know anyone who has found them. I
need these two questions to be answered before 10:00pm on 1/26 if anyone
could do so. Here are my questions:

1. Why is the size used to separate groups of plankton, rather than types of
organisms?

2. What are the pros and cons of an organism having its larva form a part of
the plankton for a portion of its developmental stages?

Thank you for taking the time to read this and thank you very much to anyone
who can help me, it is greatly appreciated.

Thank You,
Joel Seay

[Joel Seay]

Somebody pointed this out to me in a response E-mail. I can't believe I
didn't think about it, but I live in the Eastern time zone in the US (I'm in
Orlando)

Joel

[Aaron Wyckoff]

General disclaimer: I know rather little about marine biology (or
biology in general). The following answers are what seems logical to
me, and are essentially guesses with no basis in experience or
knowledge.

Joel Seay wrote:
>
> 1. Why is the size used to separate groups of plankton, rather than types of
> organisms?

I can think of three logical reasons why size might be used for
classification, although I do not know if any of the following are
actually true.

a. If there is a correlation between the average size of plankton and
their evolutionary development (i.e., if more evolved plankton are
typically larger), then organizing plankton by size would also organize
them by the era in which they first appeared.

b. If there is a correlation between the average size of plankton and
the depth at which they are commonly found (assuming we are talking
about oceans), then organizing plankton by their size would also give an
indication of the environment in which they are found.

c. If marine plants and animals that consume plankton generally restrict
their diet to one particular size of plankton, rather than one
particular species or genus, then classifying plankton by size would
also classify them by the species that feed upon them.

d. None of the above.

>
> 2. What are the pros and cons of an organism having its larva form a part of
> the plankton for a portion of its developmental stages?

I haven't a clue, although if the larva consume the plankton then a
ready food source would be a pro, while being consumed by other
organisms that are also consuming the larva would be a con.

Aaron Wyckoff
(sorry, I teach social studies, not biology)