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• Invertebrates


  Animals that lack a backbone
• Invertebrates account for more than 95% of known animal species
• Invertebrates are morphologically diverse and occupy almost every habitat on Earth
• Sponges (Porifera)


  • Lack tissues
  • Have groups of similar cells that act as functional units
  • Are filter feeders, capturing food particles suspended in the water that passes through their body
  • Are sedentary and live in marine waters or fresh water
  • Most are hermaphrodites
• Cnidarians


  • Have true tissues
  • Have diversified into a wide range of both sessile and motile forms including jellies, corals, and hydras
  • Are carnivores that use tentacles to capture prey
  • Live in marine waters
  • Exhibit a relatively simple diploblastic, radial body plan
• Lophotrochozoans


  • Bilaterian animals have bilateral symmetry and triploblastic development
  • Most have a coelom and a digestive tract with two openings
  • Includes flatworms, rotifers, acanthocephalans, ectoprocts, brachiopods, molluscs, and annelids
• Flatworms (Platyhelminthes)


  • Free-living, live in marine, freshwater, and damp terrestrial habitats
  • Have a gastrovascular cavity with one opening
  • Planarians have light-sensitive eyespots and centralized nerve nets
  • Planarians are hermaphrodites and can reproduce sexually, or asexually through fission
  • Parasitic species absorb nutrients directly from the host's intestine, have a scolex with suckers and hooks for attaching to the host, and have proglottids that contain sex organs and form a ribbon behind the scolex
• Molluscs


  • Phylum Mollusca includes snails, slugs, oysters, clams, octopuses, and squids
  • Most are marine, though some inhabit fresh water or terrestrial
  • Are soft-bodied animals, but most are protected by a calcium carbonate shell
  • Gastropods move slowly by a rippling motion of the foot or by cilia, and most have a single, spiraled shell
  • Bivalves have a shell divided into two halves, some have eyes and sensory tentacles, and the mantle cavity contains gills used for feeding and gas exchange
• Ecdysozoans


  • Are the most species-rich animal group
  • The two largest ecdysozoan phyla are arthropods and nematodes
• Arthropods


  • Have modified appendages that are jointed and come in pairs, and function for walking, feeding, sensory reception, reproduction, and defense
  • The body is completely covered by the cuticle , an exoskeleton made of layers of protein and the polysaccharide chitin
  • Have eyes, olfactory receptors, and antennae that function in touch and smell
  • Are important as food for humans, fish, and birds, and produce economic materials such as silk and honey, and are used in research and experiments
• Deuterostomes


  • Include echinoderms (sea stars and sea urchins) and chordates (vertebrates with a backbone)
• Animals are multicellular, heterotrophic eukaryotes
• All animals must obtain nutrients and oxygen, fight off infection, and produce offspring
• Animals have specialized muscle and nerve cells that enable them to detect, capture, and eat other organisms
• The evolutionary adaptations that enable survival result in a close match of form to function
• Four major tissue types in animals

  • Epithelial
  • Connective
  • Muscle
  • Nervous
• Some body plans have been conserved, while others have changed multiple times over the course of evolution
• Animals can be categorized according to the symmetry of their bodies, or lack of it :

  • Radial symmetry : animals that have a top and a bottom, but no front and back, or left and right

  Radial animals are often sessile or planktonic (drifting or weakly swimming)

  • Bilaterally symmetry : these animals have:

  A top side and a bottom side ,A right and left side , Front and back ends , Many also have sensory equipment, such as a brain, concentrated in their anterior end , they typically move actively and have a central nervous system
• tissues :

  Animal body plans vary according to the organization of the animal’s tissues.

  3 germ layers are developed during embryonic development, these layers form the various tissues and organs of the body :

  1. Ectoderm : the layer covering the surface of the embryo
  2. Endoderm : the innermost layer and lines the lining of the digestive tub .
  3. Mesoderm : the middle tissue layer.
• animals that have only 2 germ layers, ectoderm and endoderm. (no middle “mesoderm”) : diploblastic

  include : cnidarians
• animals have ectoderm, endoderm and mesoderm. (all 3) : tripoblaastic

  All bilaterally symmetrical animals are triploblastic
• body cavities :

  1. Coelomates : animals that possess a true coelom derived from mesoderm
  2. Pseudocoelomates : animals that possess a pseudocoelom, a body cavity derived from the mesoderm and endoderm.
  3. Acoelomates : triploblastic animals that lack a body cavity
• the inverbrates groups :

  1. sponges
  2. cnirdarians
  3. Lophotrochozoans
  4. Ecdysozoans
  5. Deuterostomes
• Lophotrochozoans : a clade identified by molecular data, have the widest range of animal body forms.

  1. have bilateral symmetry and triploblastic development.
  2. Most have a coelom and a digestive tract with two openings
  3. The clade Bilateria contains: 1-Lophotrochozoa. 2- Ecdysozoa. 3- Deuterostomia.
• lophotrochozoans include :

  • Flatworms
  • Rotifers
  • Acanthocephalans
  • Ectoprocts
  • Brachiopods
  • Molluscs
  • Annelids
• lophotrochozoans : flat worms :

  1. Phylum Platyhelminthes Free-living, live in marine, freshwater, and damp terrestrial habitats.

  2. Flatworms have a gastrovascular cavity with one opening.
• what are the species of Flatworms (Platyhelminthes)?

  1. free living species
  2. parasitic species
• free living Flatworms (Platyhelminthes) example :

  Planarians .

  have light-sensitive eyespots and centralized nerve nets.

  are hermaphrodites and can reproduce sexually, or asexually through fission.
• parasitic Flatworms (Platyhelminthes) :

  They absorb nutrients directly from the host’s intestine.

  -The scolex contains suckers and hooks for attaching to the host.

  -Proglottids are units that contain sex organs and form a ribbon behind the scolex.

  example : tape worm
• Most molluscs are marine, though some inhabit fresh water or terrestrial.

  are soft-bodied animals, but most are protected by a calcium carbonate shell
• the two types of molluscs :

  1. gastropods
  2. bivalves
• gastropods characterstics :

  1. move slowly by a rippling motion of the foot or by cilia.
  2. Most have a single, spiraled shell that functions in protection from injury, dehydration, and predation
• Bivalves characteristics :

  1. have a shell divided into two halves.
  2. Some bivalves have eyes and sensory tentacles.
  3. The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange.
• lophotrochozoans : Annelids :

  Annelids are coelomates with bodies composed of a series of fused rings.

  example : leeches
• Leeches include predators of invertebrates and parasites that suck blood. It has medical importance in treating many diseases
• A single-celled organism (such as the Amoeba) has a sufficient surface area to carry out all necessary exchange.
• More complex animals are composed of compact masses of cells, with an internal organization much more complex
• Body plan adaptations such as specialized, extensively branched or folded structures enable sufficient exchange with the environment.
• Cnidarians ancestral protist?

  eumetazoans
• Sedentaria are clades of ?

  Annelids.