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 All multicellular & eukaryotic  Cells lack cell walls and come in a variety of shapes.  Ingestive heterotrophs (take in food and internally digest.

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Presentation on theme: " All multicellular & eukaryotic  Cells lack cell walls and come in a variety of shapes.  Ingestive heterotrophs (take in food and internally digest."— Presentation transcript:


2  All multicellular & eukaryotic  Cells lack cell walls and come in a variety of shapes.  Ingestive heterotrophs (take in food and internally digest it).

3  Have some type of skeletal support  Exoskeletons found in arthropods cover the outside of the body but limit size.  Endoskeletons found in all vertebrates are found inside the body and are made of cartilage and/or bone.

4  Worms have fluid-filled internal cavities giving them skeletal support.  Sponges have the simplest skeleton.  May be sessile (attached and non-moving) or motile (able to move around).

5  Muscular tissue provides energy for movement.  Reproduces sexually.  Shows levels of organization including cell, tissue, organ, and system.

6  Most show division of labor among cells.  Cells are specialized for particular functions.  Cell junctions hold individual cells in a tissue together. They link neighboring cells.  Most vertebrates have a backbone or spine made of repeating bones called vertebrae that protect the spinal cord.  Some show cephalization (have a head with sensory organs concentrated there).

7  Simplest animals  Contains the greatest number of animal species  Most found in water  Do not have a backbone  Includes sponges, cnidarians, flatworms, roundworms, annelids (segmented worms), mollusks, arthropods, and echinoderms.

8  More complex animals  Most have a backbone  Includes fish, amphibians, reptiles, birds, and mammals.

9  Dorsal is the back or upper surface  Ventral is the belly or lower surface  Anterior head or front end  Posterior is the tail or hind end opposite the head  Oral surface in echinoderms is where the mouth is located (underside)  Aboral surface in echinoderms is the surface opposite the mouth


11 Symmetry

12 Also called asymmetrical

13  Symmetry is the arrangement of body parts around a central plane or axis  Asymmetry occurs when the body can’t be divided into similar sections (sponges)

14  Radial symmetry occurs when body parts are arranged around a central point like spokes on a wheel (echinoderms)  Most animals with radial symmetry are sessile (attached) or sedentary (move very little)


16  Bilateral symmetry occurs when animals can be divided into equal halves along a single plane  Organisms will have right and left sides that are mirror images of each other  More complex type of symmetry

17  Animals with bilateral symmetry are usually motile  Animals have an anterior and posterior ends  Show cephalization (concentration of sensory organs on the head or anterior end)



20  Occurs whenever animal bodies are divided into repeating units or segments  Found in more complex animals  Earthworms show external segmentation, while humans show internal segmentation (vertebrae of the backbone)  Segments may be fused together such as cephalothorax covering chest & head of a crayfish

21 Segmentation cephalothorax

22 Tissue Development

23  All animals reproduce sexually, but some also reproduce asexually (sponges bud & flatworms fragment)  Zygote is the fertilized egg all animals form from  Zygote undergoes rapid cell divisions known as cleavage to become hollow ball of cells called blastula  Blastocoel is the central cavity of the blastula

24  Blastula folds inward at one point to form an opening & two cell or germ layers; process called gastrulation  New cup-shaped structure with 2 cell layers is called the gastrula  Archenteron is the deep cavity of the gastrula that forms the primitive gut Blastula

25  Inner germ layer called endoderm & outer germ layer called ectoderm  Opening may become the mouth or the anus  Protostomes (mollusks, arthropods, & annelids) develop mouth from blastopore, while deuterostomes (echinoderms & vertebrates) develop an anus from blastopore

26  Some animals form a third germ layer in the middle called mesoderm  Cells differentiation during development changing their shapes to fit their function ( neurons or nerve cells become long to conduct messages)

27  Form tissues, organs, & systems  NOT present in sponges  Ectoderm (outer) – forms skin, nerves, sense organs  Endoderm (inner) – forms liver and lungs  Mesoderm (middle) – forms muscles & other systems

28  Sponges have NO tissues or organs, only specialized cells  Cnidarians like jellyfish & coral have only two body layers & one body opening (mouth/anus) into gastrovascular cavity  Cnidarians have outer epidermis & inner gastrodermis with jelly-like mesoglea between the layers

29  All worms, mollusks, arthropods, echinoderms, and vertebrates have three cell layers ◦ Ectoderm ◦ Endoderm ◦ Mesoderm

30 Embryonic Cleavage

31  Cleavage – rapid mitosis (cell division) of zygote  Radial Cleavage – cells divide parallel or perpendicular to axis to each other

32  Spiral Cleavage – cellular divisions occur diagonally, in a twisting pattern


34 Stages of Development

35  Animals with Indirect development go through immature (larval) forms  Larva does NOT resemble adult  Cnidarian (jellyfish, coral, & sea anemone) larva called Planula

36  Mollusk (squid & octopus) larva called trochophore  Echinoderm (starfish) larva is called Dipleurula

37  Usually found in arthropods  May be complete or incomplete  Incomplete Metamorphosis: egg nymph adult  Complete Metamorphosis: egg larva pupa adult


39 Body Cavities

40  Internal body cavity fully lined with mesoderm  Body organs suspended in this cavity

41  Acoelomate animals have solid bodies filled with cells  Acoelomate animals include sponges, cnidarians, & flatworms

42  Pseudocoelomate animals (roundworms) have a functional body cavity NOT fully lined with mesoderm


44  Spongin & spicules  Spongin & spicules (sponges)  Limestone cases  Limestone cases (corals)  Exoskeletons Chitin  Exoskeletons of Chitin (arthropods) Limits Limits size molted Must be shed or molted to grow vulnerable Animal vulnerable to predators during molting

45  Hydrostatic skeleton  Hydrostatic skeleton – fluid filled body cavity (worms) Calcium plates or Test  Inner Calcium plates or Test (echinoderms)  Bone cartilage endoskeleton  Bone and/or cartilage endoskeleton (vertebrates)

46 Exoskeletons Must Be Molted

47 Endoskeletons Grow with the Animal

48  All animals are ingestive heterotrophs  Choanocytes (specialized cells) capture & digest food for sponges  Gastrovascular cavity with one opening in cnidarians and flatworms for food to enter & leave; called two-way digestive system

49 Gastrovascular Cavity with Mouth Only (Cnidarians)


51  Animals with a one-way digestive system have a mouth and an anus  Food enters the mouth, continues in one direction through the digestive tract, and wastes leave through the anus  Includes annelids, arthropods, & vertebrates

52 Mouth anus

53  Transports oxygen & nutrients to cells  Carries away wastes & carbon dioxide from cells  Sponges, cnidarians, & flatworms do NOT have circulatory systems

54  In closed circulation, blood remains inside blood vessels until it reaches cells (annelids & vertebrates)  In open circulation, blood is pumped out of blood vessels to bathe tissues in the body cavity or hemocoel (arthropods & mollusks)

55 Open Circulation Closed Circulation

56  Taking in O 2 & releasing CO 2 diffuse  Gases can diffuse across moist surfaces (earthworms)  Gills  Gills filter O 2 from water (aquatic animals)  Lungs  Lungs take O 2 from air (terrestrial animals)

57 Skin breather Lungs Gills

58  Coordinates the activities of the animal’s body  Neurons  Neurons – nerve cells that transmit electrochemical signals  Nerve net -  Nerve net - network of neurons, very little coordination  Ganglion  Ganglion – clusters of neurons; may serve as a simple brain  Brain  Brain – control center at anterior end


60  Excretion  Excretion is the removal of nitrogen wastes from the body  Diffusion  Diffusion is used by simple aquatic animals  Flame cells  Flame cells remove wastes in flatworms

61 nephridia  Coiled tubules called nephridia remove nitrogen wastes in arthropods Kidneys  Terrestrial animals remove wastes with Kidneys paired ◦ May be paired (most vertebrates) single ◦ May be single as in birds


63  Reproduction  Reproduction is the process by which organisms make more of their own kind sexual reproduction  All animals reproduce by sexual reproduction (produce eggs and sperm) asexual reproduction  Some animals also use asexual reproduction creating identical offspring

64  Regeneration Fragmentation  Regeneration or Fragmentation is the breaking off of pieces and the re- growth of a new organism Sponges Flatworms  Found in simple animals like Sponges and Flatworms

65  Budding  Budding occurs in hydra whenever a growth on the parent is released clone  Creates a clone

66  Parthenogenesis  Parthenogenesis – females produce eggs that develop unfertilized into female organisms  Komodo dragon  Komodo dragon is an example

67  Hermaphrodite BOTH  Hermaphrodite are animals like earthworms that produce BOTH eggs and sperm NOT  Most hermaphrodites do NOT fertilize their own eggs  Mate to exchange sperm

68  External  External – sperm and eggs are released into water where they are fertilized  Internal  Internal – sperm and egg are fertilized inside the female animal’s body

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