Comparison between Non-Cephalized Phylum Porifera and Phylum Cnidaria
Kenneth Ng, A0125933E, Group A05
In the Animalia kingdom, many different phylum emerged over a long period of time due to evolution. Each phylum exhibit different characteristics which the multicellular animals have developed to adapt to the environment for survival. Examples are such as developing the ability to move from water to land and from land to water, apart from being sessile. There are also developmental structures of the animals to allow them to adapt for survival, like having exoskeletons or internal skeletal structures for support, skin for protection, muscles for locomotion, nervous system for senses and digestive systems for digesting complex food (Farabee, 2007). It is said that organisms without cephalisation are able to survive in oceans filled with planktons. Organisms without cephalisation from the ocean are mainly from phylum Porifera (a.k.a. sponges) and phylum Cnidaria.
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Both groups are diploblastic and are made up of 2 layers of cells – the ectoderm and endoderm, with a layer of jelly-like mesoglea between them (McDarby, 2001; Kimball, 2014). Both groups have species which manufacture chemicals and toxins, to prevent infection and other organisms from growing on them (Dettner, 2010). Though there are some similarities between the 2 phyla, there are distinct differences between them in the aspects of anatomy and
Moon Jellyfish are in the “Animalia Kingdom, Phylum Cnidarian, Class Scyphozoan, Order Semaeostomeae, Family Ulmaridae, and Genus Aurelia” ( Myers, 2016 ; Espinosa, ; 2016 ; Parr, 2016 ; Jones, 2026 ; Hammond, 2016 ; Dewey, 2016). The morphological description of Cnidarians are corals, sea anemones, jellyfish and hydroids. These cnidarians form a diverse phylum that contains ~9000 species, which live in aquatic (predominantly marine) environments. The phylum-defining trait of Cnidaria is the stinging cell, the nematocyte an extrusive organelle used for predation, adhesion and defense (Holstein, 1981; Lengfeld et al., 2009; Tardent and Holstein, 1982) (Steele and Technau; 2011). Also, this phylum, Cnidarians, are divided into two groups, “Anthozoa (sea anemones, corals and sea pens), which live as
Hobart and William Smith Colleges. (2017). Lab 04 BIOL 1510 Lab Manual Plant Defenses F2017 - Biology - StuDocu. Retrieved from https://www.studocu.com/en/document/hobart-and-william-smith-colleges/biology/lecture-notes/lab-04-biol-1510-lab-manual-plant-defenses-f2017/1396233/view
Adaptations in terrestrial environments involve the structural and functional qualities of the organism, to achieve the adequate intake of oxygen and other essential substances for the animal to survive, the evolution of more complex anatomical structures were required. Gravity is stronger on land than water, which means terrestrial organisms have to be more structural than aquatic organisms. Also, the balance of gas exchange with water loss is a key feature to survive in land. For example plants, when doing photosynthesis require carbon dioxide and water to produce oxygen, at the end of this process a lot of water is lost and terrestrial plants have to compensate the water being lost and the water taken from soil. Furthermore, the dispersal of gametes by wind or other animals have helped plants reproduce in large amounts and create varieties of species of the same kind. Short-term weather patterns as well as long-term climate conditions based on precipitations, temperature, wind, humidity as well as other factors are survival obstacles that organisms in land have to adapt to live; endothermic organisms have to maintain a constant internal
Marine biologists that have studied cephalopods claim that their subjects even have personalities and “that octopuses engage in play, the deliberate, repeated, outwardly useless activity through which smarter animals explore their world and refine their skills” (Scigliano, 2003). One scientist claims that her octopus even “bubble surfs” by spreading his mantle out and letting the aerator jets from his tank run under his body (Scigliano, 2003). .
There are several major trends that developed in the vertebrate group that has allowed the transition from aquatic to terrestrial life. Some of these trends are improved respiration, protective body covering, and more efficient ways to reproduce. The adaptations that have allowed the transition from aquatic to terrestrial life are: Jaws, lungs, jointed vertebrate limbs, water tight skin, amniotic egg for reproduction. In birds and mammals another adaptation that has evolved is that they are endothermic meaning they generate internal heat.
Vertebrates are known to be animals with backbones. Tooth reduction is one of the major evolutionary trends that developed among major vertebrate groups that allowed for the transition from aquatic to terrestrial life. Evolution of limbs and being able to breath air are other evolutionary trends that took placeThese trends include improved respiration and protective and insulating body coverings. More over the transition from water to land also included changing to more efficient reproductive methods like having a placenta for some animals or egg layers for other animals. Lastly, the morphology of organisms evolved such that for land they would have paired, muscular appendages used for crawling and
* Fluid – filled cavity allowed for the evolution of a hydrostatic skeleton for movement (evolved out of animals having a coelom)
The crayfish differs from the earthworm and the chordate because it has a hard exoskeleton that covers its body.
On this image, we see the external dorsal side of a preserved crayfish. As part of the largest animal phylum the Arthropoda, the body of the crayfish is segmented, with jointed appendages and exoskeleton. The paired antennae (1) are long appendages located the front of the mouth and modified for help the animal to sense touch and taste. The antennules (2) are shorter, also paired with the same function but they also help to maintain balance. The chelipeds (3) are located on the front of the thorax, and they are responsible for defence and grasping food. On the at ventral part of the thorax, we found four pairs of walking legs (4), with these legs the crayfish changes locations on the bottom of freshwater lakes, streams and also on land. They
They have gills covered by an operculum that increases respiratory efficiency by creating negative pressure that both draws and pushes water across the gills. They have a gas-filled pouch for gas exchange in low-oxygen environments that contributes to buoyancy. A few species use diffusion across their skin.
shellfish and zooplankton such as foraminifera and pteropods. These organisms, especially zooplankton, are the base of the marine food chain, as they provide energy in the form of food for animals higher up the food chain. The levels of calcium carbonate, minerals that calcifying species use to build their exoskeleton, in the ocean are disturbed by the increased amounts of carbon dioxide that is being absorbed. This new absorption is causing some parts of the ocean to become unsaturated with this important compound, and therefore making them less available to the calcifying organisms that need them. Without these protective shells, organisms are unable to survive, leading to a rapid decrease in their populations.
Cnidarians share a basic body plan, but have two distinct body forms-the polyp and the medusa. The medusa plan is essentially the polyp turned upside down. By inverting same shape, cnidarians devised two distinctive ways of living. Exactly how and when the transition occurred is uncertain, but anchored cnidarians adapted a body plan for a free-swimming life (the medusa),and may have been the first animal to swim the oceans. The medusa plan allows the jellyfish to swim through the water using muscle contractions and float with the currents.
Cnidarians (or coelenterates), including sea anemones, jellyfish, and corals, are built mostly of sheets of cells, and they exploit the large surface area of the
Coral animals begin life as free-floating larvae, but settle on the sea floor in sedentary colonies. The term "coral" applies both to these animals and to their skeletons, particularly the skeletons of stone-like corals (Discover 1997).
The tilting of the body axes of extant cephalopods. This was a result of a polyphyletic and repeated trend towards enhanced manoeuverability. The morphological body axes (anterior-posterior, dorso-ventral) are tilted perpendicularly against functional axes in the transition towards extant cephalopods.