Lab 4 Flashcards
Measurable morphological characters can be subdivided into two categories. These are?
1 - Mensual or morphometric characters
2- Meristic characters
What is an example of a mensual or morphometric character?
Length of body parts (that can be measured with a mm scale)
What is an example of meristic characters?
Fin ray counts
All measurements of the fish are ________ line projections between two reference points.
straight
What is an issue with morphometrics?
Certain absolute measurements (such as head length) could not be used to distinguish between 2 species if one was a juvenile and the other was an adult.
What method is used to overcome the inherent issue of morphometrics?
Morphometrics are expressed as proportions or percents of a fish’s SL or TL
What is SL?
Length from snout to the base of the caudal fin.
What is TL?
Length from snout to the tip of caudal fin.
What are the two fish that we will be using today?
Freshwater drum and White Perch.
______ and _________ of the mouth and jaw are important indicators of food items since they will limit the type of prey that a fish can ingest.
Size
Protrusibility
What characters will we be looking at for the gut analysis for this lab?
- Length of gut/intestine
- Mouth position
- Protrusible jaw (or not)
- Tooth type and position
- Gill rakers
How many fish will be used for the first part of the lab?
3 of each species
How many fish will be used for the second part of the lab?
1 of each species
Before cutting into the fish, what external characters should be observed?
- teeth type
- Jaw
- Gill rakers
- TL
What are the steps for the dissection?
- Cut the cheeks on both sides to look into the mouth for pharyngeal teeth.
- Open the body cavity by cutting away the body wall.
- Remove the digestive tract by cutting just behind the pharynx and in front of the anus
