Octopus has 8 arms and contains no shell. Learn vocabulary, terms, and more with flashcards, games, and other study tools. ; Unio contains a digestive gland called Green gland, which is comparable to liver of vertebrates. GENERAL CHARACTERISTICS BODY CHARACTERS : Soft Unsegmented Triploblastic No jointed appendages SYMMETRY : Bilaterally symmetrical SHELL : Externally mantle secretes a hard , brittle , calcareous shell . It is primitive with segmented body. Phylum Mollusca Characteristics. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. -Respiration by gills, book lungs and trachea. A few molluscs such as Unio possess green glands which mimic the liver in vertebrates. Many organisms belonging to this phylum have a calciferous shell. The proportion of undescribed species is very high. -Body - Head, Thorax and Abdomen(three parts). Each mollusk has a muscular organ called a foot that is used for gripping or creeping over surfaces. The number of fossil species is estimated between 60,000 and 100,000 additional species. Phylum 2. The bodies are generally very soft and are covered by the hard exoskeleton.They can be found in terrestrial regions as well as in the depths of the seas.You will be amazed to know that the size of the molluscans can range from 20 metres to one millimetre, with a few microscopic animals too. Phylum Mollusca. Generally, these animals live in water. They possess osphradia to test the chemical nature of water. Phylum Mollusca is a very diverse (85,000 species ) group of mostly marine species, with a dramatic variety of form. PHYLUM MOLLUSCA (SOFT BODY) I. CHARACTERISTICS A. The group Mollusca, established by Cuvier (1798), com­prises of almost 1,00,000 species and is the second largest animal phylum (Fig. Phylum Mollusca 1. However, both molluscs and echinoderms are triploblastic, and they possess a complete digestive system. Things to remember. Some secrete a hard shell. -Blood without haemoglobin and circulatory system open. The statocysts maintain body equilibrium. Members of the phylum Mollusca are soft-bodied animals, such as the snail, clam, squid, oyster, and octopus. Soft-bodied invertebrate covered with protective mantle that may or may not form a hard, calcium carbonate shell; Includes chitons, snails, slugs, clams, oysters, squid, octopus, & nautilus; Second largest animal phylum; Have a muscular foot for movement which is modified into tentacles for squid & octopus Phylum Mollusca and Phylum Echinodermata belong to the Kingdom Animalia. There is a between Mollusca and Echinodermata in terms of morphological, physiological and behavioural characteristics. They also possess ink glands for protection. -Bilateral symmetry, Triploblastic, segmented coelomate. This phylum can be segregated into seven classes: Aplacophora, Monoplacophora, Polyplacophora, Bivalvia, Gastropoda, Cephalopoda, and Scaphopoda. Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda.The members are known as molluscs or mollusks (/ ˈ m ɒ l ə s k /).Around 85,000 extant species of molluscs are recognized. Contains snails, slugs, octopus, squid, and the "shell fish" (clams, oysters,limpets, and scallops); second largest phylum (greater than 100,000 species) B. Neopilina is considered as connecting link between Annelida and Mollusca. -Excretion by malpighian tubules. It protects the soft body . ; Statocysts- for maintaining equilibrium of the body. Key Points on Mollusca. 2 nd largest animal phylum after Arthropoda. 3. Phylum Mollusca is the second largest phylum. Start studying Intro to Mollusca Notes and Class Gastropoda notes. 1.100). Phylum Arthropoda( Jointed Legs) – -Largest phylum. Phylum Mollusca – -Soft body animals.
2020 phylum mollusca notes