Fishes
Sweetlips are, despite their funny faces, easily recognizable as fish.
KEY CHARACTERISTICS
The word fish is used informally to describe aquatic vertebrates that look similar even though they belong to several different clades, because all are adapted to life in water. Most vertebrates we call fishes have paired fins, scales, and gills.
Feeding and Digestion Varies widely, both within and between groups: herbivores, carnivores, parasites, filter feeders, detritivores; digestive organs often include specialized teeth and jaws, crop, esophagus, stomach, liver, pancreas
Circulation Closed, single-loop circulatory system; two-chambered heart
Respiration Gills; some have specialized lungs or other adaptations that enable them to obtain oxygen from air.
Excretion Diffusion across gill membranes; kidneys
Response Brain with many parts; highly developed sense organs, including lateral line system
Movement Paired muscles on either side of backbone; many have highly maneuverable fins; the largest groups have two sets of paired fins; some have a gas-filled swim bladder that regulates buoyancy.
Reproduction Methods vary within and between groups: external or internal fertilization; oviparous, ovoviviparous, or viviparous
• A Look Back in Time
Live Birth in Devonian Seas
You might think that live birth is a recent addition to chordate diversity. Guess again. Recent fossil finds of fishes from the Devonian Period show that at least one group of fishes was already bearing live young 380 million years ago. Two incredibly well preserved fossils, including that of the fish Materpiscis, show the remains of young with umbilical cords still attached to their mother's bodies. This is the earliest fossil evidence of viviparity in vertebrates.
Artist's conception of Materpiscis giving birth
Table of Contents
- Formulas and Equations
- Applying Formulas and Equations
- Mean, Median, and Mode
- Estimation
- Using Measurements in Calculations
- Effects of Measurement Errors
- Accuracy
- Precision
- Comparing Accuracy and Precision
- Significant Figures
- Calculating With Significant Figures
- Scientific Notation
- Calculating With Scientific Notation
- Dimensional Analysis
- Applying Dimensional Analysis