Lophophore

1. Lophophore

2. Trochophore

3. Ecdysis

4. One Phylogenetic Hypothesis for Animals

5. Another Phylogenetic Hypothesis for Animals- notice that the Protosomia are divided into Lophotrochozoa and Ecdysozoa

6. Another Phylogenetic Hypothesis for Animals that is based on body cavities

7. Kingdom Animalia: Invertebrates Most animals are aquatic and most are invertebrates. There are about 35 phyla (this number depends on the systematic system that is used).

8. Review of Animal Phylogeny

9. Phylum PoriferaCharacteristics Part I Phylum Porifera (according to the new edition the separation of the sponges into two Phyla has been dropped yeah) These are sessile, mostly marine organisms that lack symmetry and true tissues. They range in height from 1 cm to 2 m. Sponges are suspension feeders with water moving one way through them (see figure below) There are about 5,500 species (@ 100 freshwater)

10. Phylum PoriferaCharacteristics Part II The body is like a sac with pores with a cavity (spongocoel) with a large upper opening (osculum; some species have more complex bodies and have several oscula). These animals are little more than a mass of cells embedded in a gelatinous matrix but the cells are specialized.

11. Phylum PoriferaCharacteristics Part III Cells Choanocytes(which resemble a protist) AKA collar cells; these flagellated cells create a current for filter feeding (AKA suspension feeding) and then the choanocytes trap food particles (which are ingested by phagocytosis) Wondering cells (amoebocytes) function in feeding, transport, and structure. These cells move through the mesohyl (a layer of gelatinous material that separates the two layers of cells making up the body wall). Amoebacytes can become other types of cells allowing for flexibility to changing environments.

12. Phylum PoriferaCharacteristics Part IV Most sponges are hermaphrodites (gametes are produced by choanocytes or amoebocytes- eggs remain in the mesohyl but sperm are released and thus they can fertilize other sponges). Sponges also reproduce asexually by fragmentation. The planulae larvae are motile and capable of dispersal. Like other living organisms, sponges may produce chemicals that could be used by humans such as antibiotics, and possibly anticancer agents.

13. Some sponges

14. Phylum CnidariaCharacteristics Part I Nearly all are marine and there are more than extant 10,000 species They have radial symmetry, and tissues but no organs. They are diploblastic and thus have no mesoderm. The ectodermis is the outer layer, and the gastrodermis is the inner layer, while the mesoglea is the substance that is located between the two layers. The basic body plan is a sac with a single body opening (functioning as both mouth and anus) into a single gastrovascular cavity which functions in obtaining nutrients as well as functioning as a hydrostatic skeleton. .

15. Phylum CnidariaCharacteristics Part II Two body plans (but some species have only one while other species have both • polyps are cylindrical and sessile. • medusa are floating, flattened polyps (mouth down). to stimuli from all directions)

16. Phylum CnidariaCharacteristics Part III These organisms are carnivores and possess specialized, stinging cells (cnidocytes). These cnidocytes are unique to the phylum and contain nematocysts (like little harpoons) to catch food and for defense. These cnidocytes are present on the tentacles allowing prey to be captured, immobilized, and then stuffed into the gastrovascular cavity. They have simple muscles and nerves but no brain. Instead they have a noncentralized nerve net (thus they can detect and can respond to stimuli from all directions)

17. Four classes of Phylum Cnidaria Please note that I am using the instead of Clade. Remember that clades are like taxa and describe groups of organisms at different levels. I prefer Class since it specifically describes a taxon or clade at a level between phylum and order.

18. Class Hydrozoa Slide 1 contains species such as Hydra, and Obelia. Most species alternate between polyp and medusa forms but Hydra exists only as a polyp

19. Class HydrozoaSlide 2 The man-of-war's body consists of a gas-filled (mostly nitrogen), bladder-like float (a polyp, the pneumatophore) - a translucent structure tinted pink, blue, or violet - which may be 3 to 12 inches (9 to 30 centimeters) long and may extend as much as 6 inches (15 centimeters) above the water. Beneath the float are clusters of polyps, from which hang tentacles of up to 165 feet (about 50 meters) in length. These pelagic colonial hydroids or hydrozoans are infamous for their very painful, powerful sting and are very common in Hawaiian ocean waters.

20. Class Scyphozoa contains the jellyfish and the medusa form is predominate (some species have no polyp forms)

21. Class Anthozoa contains the sea anemones and corals. The members of this class exist in the polyp form only. It is the largest class of the cnidarians.

22. Class Cubozoa are the box jellies, they were recently included in the Scyphozoa. Some can be fatal to humans Box Jellyfish are pale blue and transparent and bell or cubed shaped with four distinct sides, therefore the name box jellyfish. You have virtually no chance of surviving the venomous sting, unless treated immediately. The pain is so excruciating and overwhelming that you would most likely go into shock and drown before reaching the shore. So don't go swimming alone! Be sure to know the first aid procedures.

23. Phylum Ctenophora (marine comb jellies or sea walnuts). There are about 100 species and all are marine ranging in diameter from @ one to ten cm. They are similar in structure to medusae but are more complex (structurally) than cniderians to whom their relationship is unclear The comb jellies are the largest animals to use cilia for locomotion. Comb jellies have colloblasts for food capture that are located on their two tentacles.

24. Phylum PlatyhelminthesCharacteristics Part I There are about 20,000 species in marine, freshwater, and damp soil. Many are parasitic. They range in size from nearly microscopic to > 20 m long (e.g., some tapeworms). They have bilateral symmetry, and are acoelomates that are triploblastic. Note- the cniderians and ctenophores have radial symmetry and are diploblastic thus the flatworms are the first animals that we discuss that have bilaterial symmetry. They are flattened dorsoventrally from top to bottom and lack circulatory systems thus diffusion is important for transport.

25. Phylum PlatyhelminthesCharacteristics Part II They have a primitive excretory system (flame cells). The flame cells waft water through branched duct to the outside (allowing for the invasion of freshwater and terrestrial environments). There is moderate cephalization (some have definite heads) and a primitive nervous system They have only one gut opening

26. Phylum PlatyhelminthesCharacteristics Part III Many are hermaphrodites Summary of evolutionary trends: bilateral symmetry, development of mesoderm (and thus more complex organs and true muscle tissue), moderate cephalization, and a primitive excretory system (flame cells).

27. Examples of Flatworms

28. The Flatworms

29. Free living species (e.g., planarians). These flatworms move by cilia on land and use muscles for swimming. An example is Dugesia.

30. Trematodes (flukes) and monogeneans Flukes are parasitic flatworms that possess tough coverings. They have complex life cycles with multiple hosts e.g., blood flukes and liver flukes. The monogeneans are external parasites of fish that have free-living larvae

31. Cestodes (tapeworms) - parasitic with a scolex with suckers and hooks that have no digestive system (food is digested by the host) but have proglottids (reproductive sacs with eggs). Beef and pork tapeworms (Taenia) infest humans. Large tapeworms can be 20 m in length

32. Phylum Nemertea (ribbon or proboscis worms) Part I There are questions about the phylogenetic relationships of these worms. There are about 900 mostly marine species (but a few are terrestrial) They are structurally acoelomatic but have a small fluid-filled sac (used to extend the proboscis) that some zoologists view as a true coelom. These worms range in size from less than 1 mm to over 30 m.

33. Phylum Nemertea (ribbon or proboscis worms) Part II Excretory, sensory, and nervous systems similar to those found in the flatworms but they have evolved a simple closed circulatory system (with no heart, blood moved by muscle action) and a complete digestive system (having both a mouth and an anus, instead of only one opening). They are the simplest animals with a complete digestive system.

34. Phylum Rotifera (rotifers or wheel animals)Characteristics Part I About 1,800 species that live in fresh water (mostly), marine environments, or damp soil. Small (0.05-2.0 mm) pseudocoelomates with complete digestive systems and organs (lying within the pseudocoelom).

35. Phylum Rotifera (rotifers or wheel animals)Characteristics Part II Have a hydrostatic skeleton (fluid in the pseudocoelom). Some are parthenogenetic (with females only reproducing asexually) while others are reproduce sexually producing degenerate males who survive long enough to produce sperm when resistant zygotes are needed (adverse conditions).

36. Phyla Ectoprocta and Brachiopoda Phyla Ectoprocta (tiny colonial animals resembling mosses; about 4,500 species), and Brachiopoda (lamp shells which resemble bivalves; about 330 extant species but once there were over 30,000). The lophophorate animals all have a lophophore: a horseshoe-shaped or circular fold of the body wall bearing ciliated tentacles surrounding the mouth for suspension feeding.

38. Phylum MolluscaCharacteristics Part I There are more than 93,000 species (mostly marine, but freshwater and terrestrial species do occur). Most are soft-bodied, but covered by a hard shell of CaCO3. Slugs, squids, and octopuses have reduced shells or none at all. They are coelomates and protostomes

39. Phylum MolluscaCharacteristics Part II All molluscs have a similar body plan (figure 33.15) with a visceral mass that contains internal organs, a mantle (a heavy fold of tissue that drapes over the visceral mass and a water-filled chamber associated with the mantle (mantle cavity) housing the gills, anus, and excretory pores. Many species possess a rasping organ, the radula, for scraping food.

40. Phylum MolluscaCharacteristics Part III All have a muscular system for movement. Molluscshave efficient excretory systems (nepridia are present) Most have separate sexes, others are hermaphroditic. There is a ciliated larval form, the trochophore, which is also found in marine annelids, but unlike the annelids, the molluscslack segmentation. In molluscs, the thetrochophore becomes a veliger. The phylogenetic relationship to other animals is in question.

41. Phylum MolluscaCharacteristics Part IV These organisms are an important food source, and some are harmful (e.g., as hosts for disease causing organisms, or ecologically damaging species like the zebra mussel). Based on documented extinctions, molluscs as a group have experienced the largest number in recent history, These extinctions are caused by habitat loss, pollution, and interspecific interactions with competitors or predators.

42. Classes of Mollusks (four of eight).

43. Class Polyplacophora: the chitons are oval-shaped with eight overlapping plates, marine, shelled animals using their muscular foot (like snails) and graze using their radulas to scrape algae from the surface of the rocks.

44. Class Gastropoda: the snails and slugs inhabit fresh water, marine and terrestrial environments. Torsion, whereby one side of the visceral mass grows faster than the other causing the visceral mass to rotate up to 180 degrees and placing the anus and mantle cavity above the head, is unique to this class. Most of the gastropods have a single, spiraled shell for protection. Most use their radula for grazing but some species are carnivorous and bore into the shells of other mollusks or tear tissues with their radulas. Some of the cone snails are venomous.

45. Class Bivalvia: clams, oysters, mussels, and scallops that have shells divided into two halves and that are hinged at the mid-dorsal line. Their gills are used for gas exchange and for feeding. These mollusks do not possess a radula nor a distinct head.

46. Class Cephalopoda: octopuses, squids, nautiluses are all marine animals. These mollusks have large heads and are built for speed. They are the most intelligent and largest of the invertebrates. They are carnivores and possess toxins. The shell is reduced or internal except in the nautilus. They have a nervous system, sense organs, and a closed circulatory system.

47. Video Giant octopus eats shark in aquarium

48. Phylum Annelida (meaning little rings) contains the segmented wormsCharacteristics Part I There are about 16,500 species of marine, freshwater and terrestrial (moist) species that range in size from 1 mm to 3 m (the Australian earthworm). They possess an excretory system with metanephridia.

49. Phylum Annelida (meaning little rings) contains the segmented wormsCharacteristics Part II They are hermaphroditic but do not self-fertilize and some can reproduce asexually by fragmentation. They possess setae (bristles) and septa that separate the coelom, but the digestive tract, the longitudinal blood vessels, and nerve cords are continuous along the body’s length.

50. Phylum Annelida (meaning little rings) contains the segmented wormsCharacteristics Part III The digestive system consists of specialized regions. There is some cephalization. These worms have a closed circulatory system and brainlike cerebral ganglia.