MARS2014 Lecture Notes - Lecture 22: Pedal Disc, Gastrovascular Cavity, Box Jellyfish
Monday, 23 April 2018
MARS2014- Week 8 Lecture 1
Marine Zoology- Invertebrates 2
-Cnidaria:
•Have a nerve net to coordinate activities
•GVC (gastrovascular cavity) blind sac for digestion, circulation, and respiration
•Nematocyst coiled inside the Cnidocyte, has tigger called cnidocil
•Has epidermial, mesogleal, and gastrodermal (stomach skin) cells
•All carnivorous, use cnidocytes to catch prey (mainly on tentacles)
•Primary reef builders
•4 classes; Anthozoa (flower animals e.g. corals, anenomes), Hydrozoa (water
animals), Scyphozoan (cup animals/ jellyfish), Cubozoa (cube shape medusa with
tentacles on each of the four corners)
-Anthozoa: all marine, no medusa stage, partitioned GVC, complex fibrous
mesoglea, pedal disc (hold fast), siphonoglyphs (ciliated grooves at one or both
ends of the pharynx, creates current), sexual and asexual reproduction,
•Subclass:
-Octocorallia: eight orders incl. soft corals, gorgonians, & sea pens, polyps
with 8 pinnate tentacles, may be polymorphic
-Hexcorallia: 6 primary septa in GVC, never spicules in skeleton, solitary or
colonial, hard corals (e.g. stony corals), order Scleractinia
-Hydrozoa: blue bottles (colonial polyps form medusa body), fire coral,
stinging hydroid
-Cubozoa: box jellyfish (complex lifecycle), irukandji, chironex
-Zooxanthellae: photosynthetic, endosymbiotic relationship with hard coral, may
provide up to 90% of the corals nutrients
-Cthenophora (Comb jellies):
•Micro-macroscpoic
•Diploblastic
•Comb plates for locomotion
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