10 public questions tagged with this topic.
Sponges (Phylum Porifera) exhibit intracellular digestion as they lack a digestive cavity. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Animal Kingdom, Topic: Basis of classification and salient features of phyla.
Poriferans have a unique water canal system, which helps in food gathering, respiration, and excretion.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Arthropoda
Sponges (Phylum Porifera) exhibit intracellular digestion as they lack a digestive cavity.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Porifera and Cnidaria
Sponges use a water canal system to filter food particles from water. They lack tissues and exhibit cellular-level organization.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Porifera and Cnidaria
Sponges do not possess a nervous system or a nerve net. Their body functions are regulated by the water canal system.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Porifera and Cnidaria
Sponges exhibit a cellular level of organization where cells are arranged as loose aggregates without forming tissues.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Basis of Classification - Symmetry Coelom Segmentation
Euplectella aspergillum commonly known as Venus' flower basket is elegant glass sponge belonging to Class Hexactinellida found in deep bathyal waters western Pacific below 500 meters. Its skeleton constitutes entirely siliceous spicules specifically hexactine triaxon type six rays orthogonal composed hydrated amorphous silica fused into three-dimensional lattice forming cylindrical basket-like cage with sieve plate covering osculum anchoring via basal tuft. Structure exhibits glassy appearance exceptional strength optical properties. No spongin or calcareous spicules present. Siliceous composition and hexactine symmetry distinguishes hexactinellids from Calcarea with calcareous spicules and Demospongiae with combination spongin and siliceous spicules historically defined for classification and identification.
Ref: Brusca & Brusca, Chapter 7: Hexactinellida Euplectella siliceous spicules; NCBI Porifera
Poriferan embryology reveals diverse larval morphotypes including parenchymella solid stereoblastula and amphiblastula. Amphiblastula distinctive of calcareous sponges Class Calcarea and some Demospongiae characterized as hollow blastula with polarity one hemisphere composed small flagellated micromeres animal pole opposite large non-flagellated macromeres vegetal pole giving half-flagellated appearance. Free-swimming undergoes gastrulation by invagination of flagellated half then attaches metamorphoses into juvenile sponge. Polarity reflects axial specification. Presence exemplifies primitive holoblastic unequal cleavage lecithotrophic dispersal phase before sedentary adult filter-feeding existence demonstrating early evolution of larval strategies in earliest diverging animals with minimal tissue organization and cellular totipotency and settlement.
Ref: Brusca & Brusca, Chapter 7: Porifera amphiblastula larva Calcarea; NCBI Porifera
Porifera represent morphologically simplest multicellular animals at cellular grade organization lacking true tissues defined by basement membranes, no organs, no symmetry, no nervous system, no muscle, no germ layers, no gut exclusively aquatic mostly marine but few freshwater Spongillidae sessile filter feeders. Body wall contains outer pinacoderm inner choanoderm of collar cells choanocytes driving water through aquiferous system of pores canals chambers mesohyl with amoebocytes spicules silica or carbonate and spongin fibers. Reproduction both asexual budding gemmules and sexual with larvae. Totipotent cells minimal division. Thus features such as nerve net muscle gut nephridia absent distinguishing Parazoa from Eumetazoa.
Ref: NCERT Class 11 Biology, Chapter 4: Porifera no true tissues; Campbell Biology Chapter 33
Poriferan free-swimming larvae include amphiblastula hollow blastula with anterior hemisphere flagellated smaller micromeres and posterior hemisphere larger unflagellated macromeres characteristic of calcareous syconoid sponges, after inversion settles and flagellated cells become choanocytes. Parenchymella also called parenchymula or stereogastrula typical of demosponges solid structure with outer flagellated columnar epithelium surrounding inner mass of amoeboid cells. Both lecithotrophic planktonic dispersal forms. Planula belongs to cnidarians, trochophore to lophotrochozoans, veliger molluscan, bipinnaria echinoderm, nauplius and zoea crustacean decapod larvae not sponge. This concept holds high importance for NEET, CBSE board, CUET and competitive examinations focusing on comparative morphology
Ref: Brusca & Brusca Invertebrates 3rd ed. Porifera Larvae; NCERT Class 11 Chapter 4 Larval Forms
