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Phylum Ctenophora Classification.pdf

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The Ctenophora are a phylum of marine animals commonly known as comb jellies. They have transparent gelatinous bodies and swim using rows of ciliary plates. There are about 80 known species found in coastal waters. They were formerly classified under Coelenterata but are now placed in their own phylum. Ctenophorans can be divided into two classes - Tentaculata which have two tentacles, and Nuda which lack tentacles and includes only the predatory genus Beroe.

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Phylum Ctenophora: Classification and Features The Ctenophorans are a small group of firee-swimming. planktonic marine animals with transparent, delicate, gelatinous bodies. They are commonly known as sea wainuts or comb jellies. About 80 known species are present in this phylum and are abundant in coastal water. Formerly this phylum was placed under coelenterata but Hatschek (1889) placed it under a separate phylum Ctenophora. Etymolog: Greek: ktenos, comb; phoros, bearing Diagnostic Features of Phylum Ctenophora: i. Exclusively marine; solitary and mainly pelagic. ii. The radial symmetry is rendered biradial by two tentacles (radial + bilateral). ii. Body wall two layered; mesoglea is thick and has amoebocytes and smooth muscle fibres. iv. Cnidocytes absent but tentacles carry Tasso celis (colloblasts). V. Eight meridional rows of ciliary plates are present which help in locomotion. vi. Carnivorous animals having gastro-vascular cavity with mouth and anal pore. vii. Respiratory exchange takes place by diffusion. viii. Presence of luminescence. ix. Nervous system is in the form of a sub-epidermal nerve network which is particularly well developed beneath the comb rows. x. Hermaphrodite; a few reproduce asexually. Cleavage complete, determinate type, leading ulimately to a 'cydippid' larva. Scheme of Classification ofPhylum Ctenophora: The first definite description of ctenophores was given by Martens (1671). It was Hatschek (1839) who put all the ctenophores under a distinct phylum. Nearly all authors have divided ctenophores into two classes, the Tentaculate (six orders) and the Nuda (beroids only). Parker and Haswell, 1972 (as revised by Marshall and Williams, 7th edn.), has also divided clenophores into 2 classes-- Tentaculata (Mierupharyngea) und Nuda(Macroplharynge4)
However, according to Meglitsch and Schram (1991), as the groups are poorly known, separation at the class level was not attempted. The classification followed in this text is after Ruppert and followed in this text is after Ruppert and Barnes, 1994 (6th edn). abxoral se1se organ Comb rwS ana anal ore cana rctractilJe tentacl Cntaci tcntacle sheutli men Phylum Class dronal canal stalcys aboral astrevaCuBar canal canal peripherai netwirk of AstfovaKuiar canai stomach E N Tentaculata pharyt ciliary comb plates anal porec Nuda ITouth A Comb H statcy tCntacle R A papillac Out uth ctacles pharyngecal statcyst comb piates canal subtenlacular meridional canal pharynx peripheral rctwork of alimerilation Systematic Resume of Phylum Ctenophora: gonads Fig 143: A Pleurebruciua, B. Cirnoptarn.a, C" Velanun, D. CorhopBasa anet E Hurmphora Class Tentaculata: i. The members of this class possesses two tentacles. ii. It is divided into 4 orders. Examples:Hormiphore (Fig. 1.43E), Cestum and Velamen (Venus's girdle) (Fig. 1.43C). Pleurobrachia (Fig. 1.43A), Ctenoplana (Fig. 1.43B), Coeloplana (Fig. 1.43D), Bolinopsis. Class Nuda: mouth i. The representatives of this class lacks tentacles. ii. It includes only one order. swimming plates iii. They are predators on other ctenophores. Example: Beroe (Fig. 1.44). infundibulum Fig. 144: Beroe. Note that tentacles are absent.

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Phylum Ctenophora Classification.pdf

  • 1. Phylum Ctenophora: Classification and Features The Ctenophorans are a small group of firee-swimming. planktonic marine animals with transparent, delicate, gelatinous bodies. They are commonly known as sea wainuts or comb jellies. About 80 known species are present in this phylum and are abundant in coastal water. Formerly this phylum was placed under coelenterata but Hatschek (1889) placed it under a separate phylum Ctenophora. Etymolog: Greek: ktenos, comb; phoros, bearing Diagnostic Features of Phylum Ctenophora: i. Exclusively marine; solitary and mainly pelagic. ii. The radial symmetry is rendered biradial by two tentacles (radial + bilateral). ii. Body wall two layered; mesoglea is thick and has amoebocytes and smooth muscle fibres. iv. Cnidocytes absent but tentacles carry Tasso celis (colloblasts). V. Eight meridional rows of ciliary plates are present which help in locomotion. vi. Carnivorous animals having gastro-vascular cavity with mouth and anal pore. vii. Respiratory exchange takes place by diffusion. viii. Presence of luminescence. ix. Nervous system is in the form of a sub-epidermal nerve network which is particularly well developed beneath the comb rows. x. Hermaphrodite; a few reproduce asexually. Cleavage complete, determinate type, leading ulimately to a 'cydippid' larva. Scheme of Classification ofPhylum Ctenophora: The first definite description of ctenophores was given by Martens (1671). It was Hatschek (1839) who put all the ctenophores under a distinct phylum. Nearly all authors have divided ctenophores into two classes, the Tentaculate (six orders) and the Nuda (beroids only). Parker and Haswell, 1972 (as revised by Marshall and Williams, 7th edn.), has also divided clenophores into 2 classes-- Tentaculata (Mierupharyngea) und Nuda(Macroplharynge4)
  • 2. However, according to Meglitsch and Schram (1991), as the groups are poorly known, separation at the class level was not attempted. The classification followed in this text is after Ruppert and followed in this text is after Ruppert and Barnes, 1994 (6th edn). abxoral se1se organ Comb rwS ana anal ore cana rctractilJe tentacl Cntaci tcntacle sheutli men Phylum Class dronal canal stalcys aboral astrevaCuBar canal canal peripherai netwirk of AstfovaKuiar canai stomach E N Tentaculata pharyt ciliary comb plates anal porec Nuda ITouth A Comb H statcy tCntacle R A papillac Out uth ctacles pharyngecal statcyst comb piates canal subtenlacular meridional canal pharynx peripheral rctwork of alimerilation Systematic Resume of Phylum Ctenophora: gonads Fig 143: A Pleurebruciua, B. Cirnoptarn.a, C" Velanun, D. CorhopBasa anet E Hurmphora Class Tentaculata: i. The members of this class possesses two tentacles. ii. It is divided into 4 orders. Examples:Hormiphore (Fig. 1.43E), Cestum and Velamen (Venus's girdle) (Fig. 1.43C). Pleurobrachia (Fig. 1.43A), Ctenoplana (Fig. 1.43B), Coeloplana (Fig. 1.43D), Bolinopsis. Class Nuda: mouth i. The representatives of this class lacks tentacles. ii. It includes only one order. swimming plates iii. They are predators on other ctenophores. Example: Beroe (Fig. 1.44). infundibulum Fig. 144: Beroe. Note that tentacles are absent.