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INVERTEBRATES About 97 percent of all animals are invertebrates.

INVERTEBRATES About 97 percent of all animals are invertebrates. Animals are characteristically multicellular heterotrophs whose cells lack cell walls Animals likely evolved from protozoans. Kingdom Protista.

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INVERTEBRATES About 97 percent of all animals are invertebrates.

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  1. INVERTEBRATESAbout 97 percent of all animals are invertebrates.

  2. Animals are characteristically multicellularheterotrophs whose cells lack cell walls • Animals likely evolved from protozoans. Kingdom Protista

  3. At some point during their lives, animals are capable of movement. • In the most commonly encountered animals, this stage is the adult, although some animals (corals) have sessile (nonmobile) adult phases and mobile juvenile forms.

  4. Symmetry

  5. Radial Symmetry

  6. Body Cavity and Development • Acoelomate animals (like flatworms and flukes) do not have a coelom (or body cavity) • Pseudocoelomate animals (like roundworms) have a body cavity but it does not develop from splitting of the mesoderm. • Coelomate animals (humans, fish, shrimp) have a body cavity lined with mesoderm cells.

  7. Coelomate

  8. Coelomates are either protostomes or deuterostomes. • Protostomes (first mouth) are coelomates whose embryonic development shows a blastopore associated with a mouth. • Deuterostomes (second mouth) are coelomates whose embryonic development shows a blastopore associated with an anus, with a second opening forming the mouth (hence "second mouth").

  9. Segmented Bodies • Some animals have their bodies divided into segments. This allows them to specialize certain segments, such as for antennae, eyes, claws, etc. Humans, insects, and earthworms are examples of segmented animals.

  10. Sponges: The Phylum Porifera • These asymmetrical animals have sac-like bodies that lack tissues, and are usually interpreted as representing the most primitive form of animals. • Cells from fragmented sponges can reorganize/regenerate the sponge organism, something not possible with animals that have tissues. • Most zoologists consider sponges as offshoots that represent an evolutionary dead-end. Sponges are aquatic, largely marine animals, with a great diversity in size, shape, and color.

  11. Sponges (Phylum Porifera) Sponges are sessile, spending their lives anchored to a solid surface underwater. Most are marine although some live in fresh water. diploblastic; that is, the body wall is made of two layers of cells with a jellylike mesoglea between them; The body wall is perforated with pores (hence the name Porifera) through which water containing food particles is filtered. The water is drawn in through the pores by collar cells like those found in choanoflagellates. Digestion is intra-cellular (inside the cells ). dispersed by small, free-swimming larvae; about 10,000 species known

  12. Sponges can reproduce asexually (by budding or from fragments) or sexually. Sponges produce eggs and sperm that are released into a central cavity of the sponge, in which the zygote develops into a ciliated larva. The larval stage is able to move about while the adult is stationary

  13. SPONGES

  14. Poriferans • don't have mouths; instead, they have tiny pores in their outer walls through which water is drawn. Cells in the sponge walls filter goodies from the water as the water is pumped through the body and out other larger openings. The flow of water through the sponge is unidirectional, driven by the beating of flagella which line the surface of chambers connected by a series of canals. Sponge cells perform a variety of bodily functions and appear to be more independent of each other than are the cells of other animals.

  15. Radial symmetry

  16. Cnidarians are incredibly diverse in form, as evidenced by colonial siphonophores, massive medusae and corals, feathery hydroids, and box jellies with complex eyes.

  17. HYDRA

  18. The name Cnidaria comes from the Greek word "cnidos," • which means stinging nettle. • Casually touching many cnidarians will make it clear how they got their name when their nematocysts eject barbed threads tipped with poison.

  19. There are four major groups of cnidarians:Anthozoa, which includes true corals, anemones, and sea pens;Cubozoa, the amazing box jellies with complex eyes and potent toxins;Hydrozoa, the most diverse group with siphonophores, hydroids, fire corals, and many medusae; andScyphozoa, the true jellyfish.

  20. The Phylum Cnidaria • adult bodies having radial symmetry. • aquatic, mostly all marine. • have only the ectoderm and endoderm tissue layers. • Members of this phylum are characterized by stinging cells, that eject a barbed thread and possibly a toxin. Only cnidarians' have cnidocytes, a specialized cell that contains a nematocyst, a fluid-filled capsule containing a long, spirally coiled hollow thread. When the trigger of the cnidocyte is touched, the nematocyst is discharged. Some threads merely trap a prey or predator, while others have spines that penetrate and inject paralyzing toxins.

  21. Cnidarians (Phylum Cnidaria) • Characteristics: • diploblastic; two layers of cells — ectoderm and endoderm — with a jellylike mesoglea between them; • predominantly radial symmetry: body parts (e.g., tentacles) arranged in whorls. • cnidoblasts: specialized cells that secrete a stinging capsule called a nematocyst. • Food is taken through a mouth into the gastrovascular cavity. The cavity is also called a coelenteron and for many years the name of this phylum was Coelenterata. • There is no anus. • Sexual reproduction produces a free-swimming, ciliated larva called a planula.

  22. The phylum contains about 10,000 species distributed in 3 classes: • Hydrozoa Although the freshwater hydra is a much-studied representative, it is not typical of the class.produce two body forms: the sessile polyp (like the hydra) and the free-floating medusa (which disperses the species) • Scyphozoans Jellyfishes (the medusa stage is dominant). The jelly of the medusa is a much-enlarged mesoglea. • Anthozoans Sea anemones and corals. Have only the polyp stage.

  23. Two body forms occur: a mobile medusa and a sessile (not mobile) polyp

  24. Class Anthozoa: Sea Anemones and Corals

  25. Class Hydrozoa: Hydras and Portuguese Man-of-War (Physalia)

  26. Class Schyphozoa: True Jellyfishes

  27. Bilateriansbilateral symmetry • All the remaining groups of animals belong in a clade whose members share: • bilateral symmetry (hence the name); that is, dorsal-ventral and left-right axes • triploblastic (three tissue layers: ectoderm, mesoderm, endoderm) • HOX genes in one or more clusters with the genes within a cluster arranged in the same order as the body parts they affect. • The bilaterians contain two clades, the protostomes and the deuterostomes.

  28. Bilateral Symmetry

  29. Protostomes vs. Deuterostomes • protostomes ("first mouth") and the • deuterostomes ("second mouth").

  30. FLAT WORM

  31. Phylum Platyhelminthes • Bilateral Symmetry and Cephalization • The phylum as a whole has adult bilateral symmetry and cephalization (the development of a head with sensory organs, in most members). flatworms

  32. Flatworms (Phylum Platyhelminthes) • This phylum contains some 20,000 species distributed among three classes:

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