Sponge Dissection Structure/Function: The sponge is a relatively simple animal that is asymmetrical or radial symmetry. They have suspension feeders, and chaonocytes ingest food, with no cephalization. They reproduce by releasing sperm into the water, and some are asexual. They have a stiff skeleton made of spicules in a tube-like shape. They are ideal habitats for marine animals because they improve nutrient cycles and lower nitrogen levels in coral reef systems. This keeps other organisms healthy. They also have good relationships with other animals, for example, if a sponge lives on a scallop, it protects the scallop while the sponge gets good living conditions. Spicules on sponges direct sunlight, which allows them to get enough light. Ecology: Sponges generally exist in coral reefs or on rocky shores. Their color and shape varies depending on the environmental conditions. They are found at all latitudes beneath the world's oceans, from the intertidal to deep sea. Generally, they are sessile, but they have been shown to be able to move up to 4mm per day.
Jellyfish Dissection Structure/Function: The jellyfish has two simple body plans, a medusa and a polyp form. The polyp attaches itself and remains sessile. They are asexual, and reproduce by budding. They lack organs, but have specialized cells that are organized into tissues. To eat, cilia line a gastrovascular cavity, and they move food, which gets digested by vacuoles. Jellyfish breathe through diffusion and have radial symmetry about the surface of the mouth. Ecology: Jellyfish bloom formation is a intricate process that depends on ocean currents, nutrients, sunshine, temperature, season, prey, reduced predation, and oxygen concentrations. Ocean currents tend to congregate jellyfish into large swarms or "blooms", which consist of hundreds or thousands of individuals. Blooms can also result from unusually high populations in some years. Jellyfish are better able to survive in nutrient-rich, oxygen-poor water than competitors, and thus can feast on plankton without competition. Jellyfish may also benefit from saltier waters, as saltier waters contain more iodine, which is necessary for polyps to turn into jellyfish.
Squid Dissection Structure/Function: Squids are much more developed. They have a reduced exoskeleton to protect their organs. Cephalapods have an open circulatory system with a dorsal heartbeat that creates pressure. They have a complete digestive system and reproduce sexually. Squids have bilateral symmetry and have cephalization, with a complex sensory system and eyes that form images. Ecology: Squid are widespread, occuring in all the world's oceans, however they are rare in tropical and polar latitudes. Squids are important to the oceanic food chain because lots of people fish for squid and whale and birds eat them to. The squid population is growing very rapidly. This is thought to be from the dramatic decrease in fish. Squids are thought to live for only about five years and the females can sometimes produce thousands of eggs at a time.
Earthworm Dissection Structure/Function: The earthworm is a much more complex animal than previous animals we have dissected . It is segmented, our worm had 137 segments, with bilateral symmetry. It has cephalization, extracellular digestion , with a mouth, intestines, crop, and more organs. It has a full, one-way digestive system. The earthworm respires through its skin and has a closed circulatory system. Ecology: Earthworms can live in a couple of different ecosystems . The three main ones are topsoil (endogeic), deep soil (anecic), and compost (epigeic). Earthworms are very sensitive to the temperature and moisture of the soil around them so they change their depth and material according to the season. Earthworms can be decimated by chemicals in the soil so they are often killed off near farms. Grasshopper Dissection Structure/Function: The grasshopper has bilateral symmetry, and is very complex. Air enters through spiracles, to the trachea, and into the tracheoles. They have an open circulatory system and an exoskeleton for protection. It has extensive cephalization with a ventral nerve cord and ganglia. A complete digestive system is present, and reproduction is sexual. They also have wings, jointed legs, three body regions, and antenna. Ecology: Grasshoppers lay their eggs in late summer and over winter they incubate in the soil. The grasshoppers prefer warm weather because it helps with their survival. Sometimes a bacterial disease is contracted when the weather is warm and humid this cause the grasshopper to climb to a high point and die. Grasshoppers eat only leaves, they are strict herbivores.
Perch Dissection Observations 1. The body shape of the perch is relatively flat and skinny, also known as a streamline body. This helps water to rush over the sides and enable it to quickly move through the water. 2. A function of the gill rakers could be to filter tiny particles of food. They help to aid the fish's feeding. 4. The scales on the perch face towards the end of the fish, away from the head. This could help them to move more easily and efficiently through the water. 5. The perch has two nostrils.They are different from my nostrils because they do not open into the back of the mouth, which mean they aren't for breathing. Instead, they lead to organs of smell, which allows them to sense food from a considerable distance. 6. Characteristics that I observe in the gills are that there are very many tiny, thin filaments that continue to branch out. This makes for a larger surface area, which allows oxygen to rapidly diffuse into the blood. 7. The lateral line is a jelly-filled tube or canal lined with nerve endings just below the skin that opens to the outside water by tiny pores. The function of the lateral line is to detect movement in the water. If an animal in moves in the water, the jelly tube vibrates, which stimulates the nerve endings, and they send signals to the brain. This makes even a blind fish very difficult to catch.
Critical Thinking and Application 1. Endoskeletons are advantages for perches because they allow much more movement, easier mobility, protection for the organs, and breathable skin. They also dont restrict growth of the animal and they dont require very much energy to shed. If the fish were to have an exoskeleton, it would be harder to control it's temperature, and it is also a bigger deal to get hurt because the organs could be crushed. 2. The guppy produces less eggs because it has to hold them inside and then give life birth, while the perch leaves large amounts of eggs on exposed rocks. However, the guppy has a higher survival rate because the young are born live, which helps then to survive. The perch leaves their young on rocks, which makes them vulnerable to predators. 3. The function of the swim bladder is to regulate the fish's position in the water. When the perch fills the sim bladder, it is able to rise in the water. When the gas level goes down, the fish floats.
Here are some pictures of our dissections:
Here is a link to the Animal Phyla Structure table we made: