Types of Mollusks:
There are three major classes of mollusks. They are the gastropods, the bivalves, and the cephalopods. The gastropods include snails, slugs, and others. They are shell-less or single-shelled mollusks that move by using a muscular foot located on the ventral side. Their shell usually protects their bodies and they can pull completely into their shells when threatened. Bivalves have two shells that are held together by one or two powerful muscles. Bivalves include clams, oysters, mussels, and scallops. Most bivalves lead inactive lives and stay in one place for most of the time. Cephalopods are the most active of the three groups. These include octopi, squids, cuttlefishes, and nautiluses. They are usually soft-bodied and the head is attached to a single foot, which divides into tentacles or arms. They have eight or more tentacles equipped with sucking discs that grab and hold prey. Ecology of Mollusks: Mollusks feed on plants, animals, and filter algae out of the water and eat deritus. The last two points “clean up” their surroundings. Some are hosts or parasites. They are also an important source of food for numerous species. Scientists use mollusks to monitor water quality. Checking bivalves can warn biologists and public health officials about water problems. Mollusks are also important to biological research, especially because scientists believe that they are immune to cancer. Study of mollusks could possibly stop cancer in humans. |
Ecology of Annelids:
By: Brian Keena Burrous, Nick Spencer Ruiz and Rodrigo Albujar Alvarado The word annelid derives from the latin word annellus which when translated means “little ring”. The na is a basic description of its ring like appearance. Annelids spend their lives burrowing through soil and mixing it. The tunnels they make provide passages for plant roots and water and help the ecosystem, this helps plant matter decompose. They also “mine” minerals and bring them to the surface. Earthworm excretion is filled with nitrogen, phosphorus, potassium, micronutrients, and bacteria. Earthworms are important to many species because they are so low on the food chain. Annelids are divided into three classes: oligochaetes, leechees, and polychaetes. Oligochaetes contain earthworms. most worms in this class either live in soil or in fresh water. Leechees are external parasites that suck the blood and body fluids of their host. Most leechees are carnivor. Polychaetes contain sand worms, blood worms, and their relatives. They live in the water and have paired, paddle-like structures appendages tipped with setae. Setae are brush like structures. |
Perch Dissection
By: Rodrigo, Nick & Brian Observations
Observe a fish swimming in an aquarium. Describe the function of each fin used for movement. Tell whether the action provided by each fin is for propelling, steering, or maintenance balance. Which of the fins contains spines in the perch? The pectoral and pelvic fins are used for steering.
Describe the scales of the perch. Which directions do they face? What is the advantage of this? The scales of the perch seem to look similar to the scales of every other fish they all face towards the lateral side of the fish this seems to give better hydrodynamics. How many nostrils does the perch have? How they different from your nostrils? The perch has 2 nostrils and they are different from my nostrils in that the have no nose just slits. What characteristics can you observe in the gills that make them an efficient respiratory organ? In the gills there is are two types of things at the ends including the gill rakers and the gill filaments. Describes the lateral line. What is the function of the lateral line of a perch? Endoskeletons are used for support in simpler organisms, as while as give a place for muscles attach and allows muscular forces to be transferred. Critical Thinking and Application While many invertebrates have an exoskeleton, vertebrates such as fishes have an endoskeleton. Of what advantage is the endoskeleton to these animals? Endoskeletons are used for support in simpler organisms, as while as give a place for muscles attach and allows muscular forces to be transferred. The perch fertilizes its eggs externally and leaves them exposed on rocks. The guppy fertilizes its eggs internally and gives birth to live young. Which fish produces fewer eggs? Compare the survival rate of these two species. Perches can fertilize about 25,000 eggs compared to guppies mere 40 maximum. The survival rate of baby guppies is sometimes low in captivity because they often turn around and eat their own young. Most baby perches also don't survive, making their survival rates very similar. The Perch possesses a gas-filled structure called the swim bladder. What is the function of the swim bladder The function of a swim bladder is to change the level that it swims at. By increasing oxygen in the bladder, the fish raises “elevation” and lowers by releasing air. Certain fish that live deep in the ocean have chemicals in their skin that make them luminescent. What advantage is this characteristic to these fish. |
2. Due to new conditions, adaptive radiations happened in chordates and it allowed them to obtain things like jaws, appendages, etc. Sometimes these adaptive radiations produce species similar in appearance and behavior, but are not closely related. This trend is called convergent evolution. An example of this is the similarity of birds and bats.
There are many ways that chordates control body temperature. One way is ectothermy, where body temperature is mostly determined by the environment. This is used by lizards and snakes. Endothermy is where an animal can control its body temperature form within, birds and mammals are some examples. Birds conserve body heat with their feathers, while mammals use body fat and hair for insulation, and can get rid of excess heat by panting or sweating. Many vertebrates are filter feeders, while others are carnivores, and use their sharp teeth to eat their food. Depending on their feeding habits, vertebrates have varying organs and digestive systems that are adapted for them. Aquatic chordates use gills for respiration, while land chordates use lungs. Gill circulatory systems are very simple and are single-loop. They only pass through the heart once. Whereas lung cycles pass through the heart twice. Excretory systems eliminate nitrogenous wastes from the body. In chordates, gills are an important role in excretion, but vertebrates rely on kidneys that remove wastes from the blood. Ammonia is excreted from fishes directly from the gills, but vertebrates change ammonia into urea, a less-toxic compound before urination. Most chordates have very complex systems that allow them to respond to stimuli in their environment. They have olfactory bulbs (smell), a cerebrum (the thinking area of the brain), an optic lobe (vision), a cerebellum (coordinates movement and controls balance), a medulla oblongata (controls function of internal organs) and a spinal cord. Nonvertebrate chordates lack bones but have powerful muscles that they use to swim. Because of this, vertebrates are much more powerful. They all have an internal skeleton of bone and cartilage as well as muscles. 3. Fish feed in every possibly way. Some of the ways are herbivores, carnivores, parasites, filter feeders, and detritus feeders. Fishes exchange gases using gills. Gills are made up of threadlike filaments. They pull oxygen rich water into the gills where the filament collects the oxygen and then the oxygen poor water is expelled out the back. Some fish have adaptations that allow them to survive in oxygen poor water and use lungs to get air. Fishes have closed circulatory systems with a heart that pumps blood throughout the body. The fish’s heart is made of of four parts, the sinus venosus, atrium, ventricle, and bulbus arteriosus. The sinus venosus is a sac that collects blood from the fishes veins before it is pumped to the atrium. The atrium is a large, muscular one way compartment for the blood that is about to go into the ventricle. The ventricle is a large muscle that does all of the actual pumping of the blood. The blood then is pumped to the bulbus arteriosus, which leads to a blood vessel leading to the gills. Most fishes rid themselves of waste through ammonia. Some wastes diffuse through gills into the surrounding water. |