Eli, Living things captured my interest when I was a boy about 7 years old. I started collecting them, alive, and bringing them back home. I tried to keep them alive and then I often saw wonderful changes that they underwent as they grew and became adults. That fascination with life is what made me be a biologist.
Hector, I chose to be an insect biologist rather than an entomologist because I had the mistaken idea that most entomologists want to kill insects while I was more interested in studying the growth and development of insects. The modern entomologist certainly is trained to be interested in controlling insect populations through natural means and to minimize the use of insecticides. It is important to research the area that you are interested in as thoroughly as possible. Ask a lot of questions and try to find people who actually do the things you think you want to do. In the end I am glad that I took the more general route of becoming a biologist since I have diversified during my later career to study lobsters and various fish species as well as plants.
Mary, How to tell males from females depends on the group and the
species. If you mean Echinoderms, it is impossible to tell the sex of
an echinoderm from just looking at it. One experimental way used by
developmental biologists is to inject the sea urchin, sand dollar or
star fish with a potassium chloride solution. This injection causes a
fertile male or female to secrete its gametes. If it secretes the mm
size eggs, it is a female. If it secretes the very fine sperm cloud, it
is a male. Scientists who want to study the newly fertilized eggs of
echinoderms must collect or purchase at least 4 or 5 individuals of a
species in order to improve the chance of getting at least one male,
providing sperm, and one female, providing the eggs.
If you mean fish, the sex of some fish can be determined by external
inspection, i.e. they exhibit sexual dimorphism, the male looks different from
the female. However, many fish can not be told apart except by disection to
find ovaries in a female and testes in a male.
If you mean insect, most insects can be told apart by external
inspection. Males and females may have secondary sexual characters. In
cockroaches, which we talked about in class, the males have more
abdominal segements showing; so if you count the number of visible
abdominal segments you can tell whether you have a male or female.
Aljandra, Yes, we study several cell types in the zebrafish. We have used several types of microscope to see the cells of a zebrafish:
Aljandra, Small fish are eaten by bigger fish. Often a heavily digested fish in the stomach of another can be identified by the "ear stones" or otoliths of the digested fish. The ear stones are a part of the fishes sensory system that allows it to tell which direction is up despite being suspended at neutral density in the water. One of the jobs of the scientists aboard the Albatross is to identify the food habits of the fish that are caught in the trawl and examined. This is done to establish the food network operating in the marine world. I have seen innumerable digested fish in the stomachs of other fish. When they are well digested they do not make a nice photo. When they have been recently eaten, they look just like an uneaten fish unless they were swallowed in chunks. Most are swallowed whole. Part of reporting the stomach contents is estimating the total volume of the contents and if there are any whole fish we record the lengths of those fish in the computer database. This allows us to know a lot about the feeding habits of each fish species.
Look at this picture of an Atlantic herring chunk with the bite marks of
the spiny dogfish whose stomach the chunk was found in:
Nicholas, I was one of the volunteer scientists aboard the Albatross IV. In
particular, I was a cutter on one of the three fish surveying teams on
my watch. My watch was the 12-6 watch which works from 12 noon to
6PM and 12 midnight to 6 AM. The other time I could sleep or recreate.
When a trawl is brought on deck into the checker, the scientists sort
the fish in the checker and then go about sampling the fish to determine
how many of each type of fish and what is their state of development.
The cutter measures, weighs and then cuts the fish open to determine its
sex, maturity and stomach contents. The cutter's partner is called
the recorder. The recorder runs the touch screen computer and records
information that the cutter reports about each fish. Here is a picture
of a cutter and recorder at their workstation:
In this picture Peter Chase is a scientist (on the 6-12 watch) who works for the National Marine Fisheries, he is not a volunteer. Peter's recorder is Amy Poe, a volunteer scientist from Oregon. In Oregon Amy runs a sail making business. She volunteered because she was interested in what the National Marine Fisheries did in their Groundfish Survey. In this photo Peter has paused and is waiting to get an ID label from Amy to put through the gills of the herring Peter is holding. Some info about the fish can not be determined at sea. If the team decides to send the fish back to shore for further examination, a bar tag is printed by the computer to attach to the fish which will allow the people on shore to know exactly where this fish was caught during the survey.
I will answer the remaining questions as I find time in the coming weeks.
Joe