Insects, spiders and crustaceans phylum Arthropoda Snails, clams and squid phylum Mollusca Starfish and sea urchins phylum Echinodermata The invertebrates are worth mentioning because they represent the evolutionary history of the vertebrates. Some people find it intriguing that, of the invertebrates, our closest relatives are starfish and sea urchins.
Phylum Chaetognatha - sp. These tiny little predators are only cm. But they are incredibly abundant. They are the most abundant carnivore in the ocean. They are the tiger sharks of the plankton.
The tiny moveable hooks that surround the mouth, and give these creatures their name, are used to capture prey. Prey are injected with a tiny jolt of tetrodotoxin, the same paralytic poison found in some Japanese puffer fish.
They lack circulatory, respiratory and excretory organs, relying entirely on diffusion. They are living fossils, going back essentially unchanged for about my. They represent a very early branch on the chordate tree. Phylum Hemichordata 90 sp.
They may be the first deuterostomes on Earth. They range in size from 2 cm to 1. They share some of the fundamental characteristics of the chordates, which we'll review later, such as a dorsal hollow nerve cord and gill slits. We used to think they also had a notochord, another chordate trademark, but closer study revealed this hypothesis to be wishful thinking.
They live in U-shaped burrows in the ocean floor. Notice the slits in the side of the pharynx. These pharyngeal gill slits are used for gas exchange and feeding. This obscure little structure will eventually give rise to the vertebrate jaw, a marvelous example of evolutionary constraint - evolution is constrained to run in certain channels.
All subsequent evolution has to start with what's already there. They share a common ancestor with echinoderms, a fact we deduce from their similar larval forms dipleurula larvae and other developmental similarities. This larval form, incidentally looks strikingly similar to the trochophore larvae of annelids and molluscs.
Phylum Chordata Subphylum Urochordata - 1, sp. They are covered with a cellulose cloak, or tunic, which gives this group its name. They exchange gases and filter feed by means of their pharyngeal gill slits.
They rely on two prominent siphons, an incurrent and excurrent siphon, to pull water through their bodies.
The pharynx is lined with cilia, which draw water in. The suspended organic particles stick to a layer of mucus in the pharynx, and are later eaten. These siphons are convergent with mollusc siphons. Tunicates look a bit like molluscs, and a bit like a transparent sponge, and may even function like these organisms, but these similarities are entirely superficial, and the three groups are not directly related.
Although these curious animals don't especially look like us, they are very derived from their presumably bilateral and motile ancestors. The larvae of tunicates looks very much like a little tadpole. One of the strongest theories of vertebrate origins suggests that vertebrates arose from tunicate larvae by a process called neoteny.
In neoteny, the juvenile form becomes capable of sexual reproduction, and the adult stage is completely bypassed. Subphylum Cephalochordata - lancelets, Amphioxus later renamed Branchiostoma.
Lancelets are very common in shallow water. They are usually hard to see because they bury themselves in the sand, with only the head end sticking out, so they can filter feed by means of the gill slits in their pharynx.
As you might expect of a sedentary filter feeder, their cephalization is greatly reduced.and Acoustics 5 5 T 3 25 75 Core 3 – Major Practical I 3 2 P 3 40 60 Allied Paper II – Theory 5 5 T 3 25 75 Practical 3 2 P 3 40 60 PART IV 1(a) Basic Tamil II (or) 2 2 T 3 25 75 1(b) Adv.
Tamil II (or) 2 2 T 3 25 75 1(c) Non-major elective II 2 2 T 3 25 75 2. Port Manteaux churns out silly new words when you feed it an idea or two.
Enter a word (or two) above and you'll get back a bunch of portmanteaux created by jamming together words that are conceptually related to your inputs.. For example, enter "giraffe" and you'll get back words like "gazellephant" and "gorilldebeest".
Other animals, such as insects, have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals.
Life is a characteristic that distinguishes physical entities that have biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have ceased (they have died), or because they never had such functions and are classified as vilakamelia.coms forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria.
What is the project about? What are the goals? A Black light is the name given to a lamp emitting UV radiation and very little visible light. Ultraviolet radiation itself is invisible, but illuminating certain materials with UV radiation prompts the visible effects of fluorescence and phosphorescence.
The major components of the avian digestive system are the alimentary canal plus several accessory structures. The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.