- Slides: 14
Kingdom Animalia: Sponges & Cnidarians Learning Target Objectives (I can …): • List characteristics of animals (especially invertebrates), including their type of symmetry. • Distinguish between the 3 germ layers and the structures that develop from them. • Differentiate between and describe sponge and cnidarian structures (anatomy) and physiology (function). • Compare and contrast sexual and asexual reproduction in both sponges and cnidarians. • Give examples of polyp and medusa body forms.
Vocabulary: Invertebrates * symmetry (spherical, bilateral, radial) * anterior * posterior * dorsal * ventral * cephalization * germ layers (ectoderm, mesoderm, endoderm) * sponges * pores * sessile * osculum * spicules * collar cells * filter feeding * amebocytes * spongin * budding * gemmules * regeneration * larva * hermaphrodites * cnidocytes * coelenterates * radial symmetry * scyphozoa * anthozoa * hydrozoa * nematocysts * planula * cilia * basal disks * meiosis
Kingdom Animalia -all heterotrophic - all multicellular - all have a similar embryonic period - all eukaryotic - no cell walls ______ ______ ______ Invertebrates = animals with NO backbone (95 - 97% of all animals are invertebrates. ) Some of these are identified by shape (including symmetry). Symmetry – how body parts are arranged around a point or central axis
Types of Symmetry: 1) spherical symmetry – ball shaped (may be hollow). Any plane passing through the center makes similar halves. 2) bilateral symmetry – can be divided in half along 1 line/plane making each half appear the mirror image of the other. 3) radial symmetry – any plane through its central axis makes mirror image halves. Ex: cylinders - most common in animals the don’t move around much or at all Ex: hydra
Bilaterally symmetrical animals have: Anterior end – front end or “head” end Posterior end – hind end or “rear” end Dorsal surface – top of upper surface Ventral surface – bottom surface When nerve tissue and sensory organs are concentrated at the anterior end, it’s called cephalization. Most multicellular organisms have a germ layer which develops & specializes into 3 layers: 1) ectoderm – becomes the outer body covering 2) mesoderm – middle layer, may form inner body linings (mesentery) and muscles 3) endoderm – innermost layer, forms the gut lining
Phylum Porifera (pore bearer) – Sponges - pores = holes - once (sometimes still) used as sponges - sessile – attach themselves to a surface and don’t move (don’t relocate). Much like a plant. This means food has to come to the sponge. - aquatic (live in water) Sponge Structure & Function: - hollow, sac-like body closed at the bottom - osculum – fairly large opening at the top of the body - have ectoderm (pinnacoderm) & endoderm and a jellylike substance (mesoglea) which sometimes contains spicules (spikes) for support & protection - No true mesoderm - collar cells (choanocytes) with flagella
These collar cells line the inside of the body tube. Their movement draws water & food particles through the small pores, into the central chamber, and out the osculum. Food is filtered out by the collar cells. This is called filter feeding. Sponges eat mostly bacteria, small algae, and protozoans. Amebocytes – cells that move like an ameba while carrying food particles to and waste particles away from other body cells. (Wastes leave through the osculum. ) Spongin – hard substance that gives sponges a simple skeleton for support. This is what remains after the sponge dies. This is what was used as a “sponge” in homes.
Porifera (Sponge) Reproduction Asexual: Budding – small growths, “buds, ” begin and break off into new sponges. Gemmules – special “buds” of food filled amoebocytes that can survive in harsh environments that may kill the adult sponge. (Dormant stage) Regeneration – the re-growth of an organism or of its parts into a complete organism. (Each piece of a cut up sponge can re-grow. ) Sexual: Sperm enters the pores and is carried by the amoebocytes to an egg. This forms an immature larva form with flagella so it can swim to a new location, attach to something, and mature. Some sponges are hermaphrodites, that means they produce BOTH eggs & sperm. This does NOT mean they can be self-fertile!
Phylum Cnidaria: - all live in water, most in salt water - characterized by cnidocytes, (stinging cells) - coelenterates (have a hollow gut) - also have tentacles Some examples include: sea anemones, corals, jellyfish, hydra Cnidarian Body Forms: Polyp – vase shaped, sessile (doesn’t move), attach to rocks, etc. , mouth points upward. Medusa – free-swimming, umbrella shape, mouth points downward
Cnidarian Body Structure: A) 2 tissue layers: 1) endoderm – inner layer 2) ectoderm – outer layer (The mesoglea – is a jellylike material between the 2 tissue layers) B) tentacles – long, arm-like structures with coiled stingers inside the cnidocytes (which kill large prey) The tentacles draw food into the mouth. Waste materials also exit through the mouth. * All cnidarians have tentacles surrounding their mouth. * Cnidarians have radial symmetry.
3 Classes of Cnidarians: 1) Scyphozoa – spend most of life cycle as medusae (Ex: jellyfish) 2) Anthozoa – live only as polyps (Ex: anemones & coral) 3) Hydrozoa – include organisms that are either medusae or polyps or alternate between the two. -----------------1) Class Scyphozoa: “cup animals” - medusa is dominant form - jellyfish - nematocysts (coiled stingers) within cnidocytes may contain deadly poison (Ex: “sea wasp” jellyfish off Australia’s coast)
Jellyfish Reproduction: Sexual reproduction occurs in the medusa form. Male jellyfish release sperm and females release eggs into the water. Fertilization results in a planula that anchors to the seafloor, etc. (after a short “swim” using cilia). This becomes a polyp which asexually buds into stacks of medusae which soon separate and become free swimming. (Medusa reproduces sexually. Polyp reproduces asexually. ) 2) Class Anthozoa: “flower animals” - polyp form - includes sea anemones and corals - basal disks attach polyps to rocks, etc.
Coral: - live in huge colonies of small polyps - produce calcium shells that cement together. These remain behind and form a base for more coral after the polyp dies. - only live in warm, shallow water - have symbiotic relationship with algae. Algae lives in coral cells providing oxygen to coral. Anemone: - no shells - eat fish, etc. - symbiotic relationship with clown fish - larger than coral polyps
3) Class Hydrozoa: - polyps that can move by: a) releasing bubbles at the basal disk & then floating off, or by b) bending end over end in somersaults. - have a nerve net located in the mesoglea Hydra Reproduction: - usually asexual “budding” in warm weather - sexual reproduction in cold, fall weather. Eggs and sperm are produced by meiosis in ovaries and testes. The zygote forms a hard cover that protects it Until spring when it develops into a polyp. - some are hermaphroditic (both male & Female reproductive structures)