Filo Cnidaria EJERCICIO 8 121-138-120(EDITION 14TH) 119-133(EDITION 15TH) Goals for today Learn to recognized the Phylum Cnidaria from other animals Learn the main diagnostic characteristics Learn about some cnidarians biology Learn about the internal anatomy of anemones
Deuterostomia Ecdysozoa Lophotrochozoa Cnidaria and Ctenophora Porifera Radiate Animals
True multicellular animals Radial or biradial symmetry Simplest animals having a tissue level organization. However, tissues of radiates are not organized into organs having specialized functions. Cnidaria Main characteristics of cnidarians are: Diploblastic: two germ layers (ectoderm and endoderm).
Internal space for digestion= gastrovascular cavity. Mesoglea: is a thin non cellular layer Some have a skeleton (corals) but most radiates, have fluid in their gastrovascular cavity, and serves them as hydrostatic skeleton. Cnidaria Main characteristics of cnidarians are: Cnidarians have cnidocytes
Cnidocytes contain stinging organelles called nematocysts Each nematocysts contains a tiny capsule with a coiled thread like filament that injects a paralyzing toxin See video of nematocist sorry is in french! But excellent visualization of this works Cnidaria Main characteristics of cnidarians are:
Polymorphism- some species of cnidarians have more than one morphological kind of individual Polyp (hydroid) =sessile Medusa (jellyfish)= free-living Polyps= may reproduce by budding to form clones or colonies Medusas= reproduced sexually Cnidaria: Classification
Classes: Hydrozoa: Both polyp and medusa stages present Medusa with a velum Fresh and marine water Examples: Hydra, Obelia, Physalia Scyphozoa: Medusa stage emphasized Medusa without velum Polyp reduced or absent Enlarged mesoglea Solitary
Examples: Aurelia Anthozoa: All polyps No medusa Gastrovascular cavity is subdivided by mesenteries (septa). Examples: Metridium, corals Other classes for which we dont specimens but that you should know about: Cl. Staurozoa
Cl. Cubozoa Cnidaria: Your Tasks Exercise 8A: Phylum: Cnidaria Class Hydrozoa Genus: Hydra Hydras are freshwater solitary polyp forms, but are atypical hydrozoans because they dont have medusa stage.
Cnidaria: Hydra 1. Look at a slide of Hydra body parts: hypostome, mouth, tentacles. Can you see the basal disc? Cnidaria: Hydra 1. If you have a cross section of Hydra, try to identify the following structure. Cnidaria: Hydra 2. Hydras reproduce asexually. Check if your slide of hydra has a bud
Cnidaria: Hydra 2. Some hydra species reproduce sexually. Some species have separate sexes (dioecious) or an individual may have both (monoecious). Your instructor has hydras with ovaries. For comparison look at this photo of an hydra with testes Ovary testes Cnidaria: Hydra
3. Your instructor has staged a slide of an Hydra nematocysts Cnidaria: Something you should know Exercise 8A: Phylum: Cnidaria Class Hydrozoa Genus: Physalia Physalia physalis The man-of war is often mistaken for a jellyfish.
However, this animal is a floating hydrozoan colony, made up of four polyp types: pneumatophore (float), dactylozooids (tentacles for defense and prey capture), gastrozooids (feeding), and gonozooids (reproduction) Look at the preserved Physalia Cnidaria: Your Tasks Exercise 8A:
Phylum: Cnidaria Class Hydrozoa Genus: Obelia Obelia is a marine colonial hydroid. Obelia has both polyp (hydroid) and a tiny medusa (jellyfish). Cnidaria: Obelia 1. Look for your slide of Obelia. The colony:
Coenosarc Living part of the colony stem Perisarc Non-living protective cover that protects the coenosarc Cnidaria: Obelia 1. Look for your slide of Obelia. Reproductive polyps
Gonopore Medusa buds Gonotheca Gonangium Reproductive poly with medusae that arise by budding Cnidaria: Obelia
1. Look for your slide of Obelia. Feeding polyps Hydrotheca Hydrant Feeding polyp that captures and ingests prey Cnidaria: Obelia 1. Look for your slide of Obelia. The cycle
The life cycle of Obelia alternates between a sessile polyp stage and a swimming medusa stage. Cnidaria: Obelia 2. Look at the slide of the tiny Obelia medusa. Medusas are dioecious Cnidaria: Your Tasks Exercise 8B: Phylum: Cnidaria Class Scyphozoa Species: Aurelia aurita
Aurelia aurita moon jelly is a marine scyphomedusa. The mesoglea is thicker. Sexes are separate. The gastrovascular system has more canals. They have a tretamerous radial symmetry. Cnidaria: Aurelia 1. Take a look of scyphomedusa body parts A= mouth
B= Gonad C= oral arm D= gastric pouch E= radial canals F= ropalium (sense organ containing statocyst and ocellus) Cnidaria: Aurelia 2. Aurelia aurita life cycle Medusa
Larvae planula Strobila stages Ephyra Cnidaria: Your Tasks Exercise 8C: Phylum: Cnidaria Class Anthozoa Species: Metridium senile
Metridium senile is a common species in northern seas. They often reproduce asexually by pedal laceration, and are said to be capable of binary fission as well. Sexual reproduction also occurs. Diet is mostly small zooplankton, though they may also eat small benthic polychaetes, fish, and squid. Cnidaria: Metridium
1. Take a look at the external anatomy A= mouth B= oral disc C= tentacles D= column E= acontia (armed with nematocysts) F= pedal disc Cnidaria: Metridium
1. Take a look at the internal anatomy Cnidaria: Your Tasks Exercise 8C: Phylum: Cnidaria Class Anthozoa Corals Cnidaria: Corals 1. Observed the coral examples in the table. Make sure to note differences between them and the sponges! Corals are marine, typically living in compact
colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans, which secrete calcium carbonate to form a hard skeleton. wikipedia Cnidaria: Your Tasks 1. Observed the coral examples in the table. A coral "head", which appears to be a single organism, is a colony of myriad genetically
identical polyps. Each polyp is typically only a few millimeters in diameter. Individual heads grow by asexual reproduction of individual polyps. Corals also breed sexually by spawning. Polyps of the same species release gametes simultaneously over a period of one to several nights around a full moon. wikipedia Cnidaria: Your Tasks Blanqueamiento de Corales Although corals can catch small fish and
animals, such as plankton, using stinging cells on their tentacles, most corals obtain the majority of their energy and nutrients from photosynthetic unicellular algae called zooxanthellae. Zooxantela El blanqueamiento en los corales o "coral bleaching" se refiere a la prdida o expulsin de zooxantela en las anmonas, corales y otros organismo fotosintticos, as como tambin a la reduccin de pigmentos en la zooxantela cuando la misma expulsa las protenas que caracterizan su color. What are the consequences of bleaching for the reef?
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