Animals 1

Segmentation allowed for the evolution of animals with complex body plans, such as vertebrates having a segmented backbone and blocks of muscle.

Animals with this body plan are collectively called Bilateria.

Ciliated, soft-bodied and acoelomates

Bilaterally symmetrical animals can move through the environment in a consistent direction.

The five main advantages are cephalization, greater mobility, evolution of a body cavity, evolution of different patterns of embryo development, and evolution of segmentation.

They are mostly marine worms.

The three germ layers are the outer ectoderm (body coverings and nervous system), middle mesoderm (skeleton and muscles), and inner endoderm (digestive organs and intestines).

1. Annelida have segmented bodies, while Nematoda have unsegmented bodies. 2. Annelida possess a true coelom, whereas Nematoda have a pseudocoelom.

Porifera, the sponges.

Eumetazoa are all other animals that possess distinct tissues.

When the blastula indents, it forms a two-layer-thick ball with a blastopore (opening to the outside) and an archenteron (primitive body cavity or gut).

Into Parazoa ('near animals') and Eumetazoa ('true animals').

Radial symmetry.

Symmetry is defined as an imaginary line drawn through the animal’s body.

Townsend's mole

Platyhelminthes

Sea Slug

They have distinct tissues but no organs.

Bilaterally symmetrical

Egg and sperm produce free-swimming larvae that settle on a rock and grow into a new sponge.

Enterobius, known as pinworm, causes an itchy anus.

It leads to the formation of cells, tissues, organs, and body systems.

Examples of coelomate invertebrates include annelids, mollusks, and arthropods.

The head contains a cerebral ganglion and many have eyes.

Nematocysts.

The visceral mass contains the internal organs of the mollusc.

Active movement

The anus develops first from the blastopore.

1. Platyhelminthes are bilaterally symmetrical, while Cnidaria are radially symmetrical. 2. Platyhelminthes have a more complex body structure with organs, whereas Cnidaria have a simpler body plan with a gastrovascular cavity.

Cnidaria have specialized cells called cnidocytes for capturing prey, and they exhibit a more complex body structure with a true tissue organization, unlike Porifera which lack true tissues.

They have only a single opening for the digestive cavity.

Parazoa are animals that lack true (specialized) tissues and organs, but have a few distinct cell types.

Eumetazoa have distinct tissues and specialized cells for specific functions.

Bilaterians can be divided into Protostomes and Deuterostomes.

Yes, new species of animals are still being discovered.

Annelida are segmented worms with bodies built of repeated units, are coelomates, and undergo protostome development.

What do all animals have in common?

Polyp (sessile) and medusa (motile).

Open and closed circulatory systems.

Cephalization is the evolution of a definite brain area, involving the grouping of nerve cells into a brain at the anterior end of the body.

Digestive tissue originates from the endoderm.

No, bivalves do not have a radula.

Amoeboid cells in the mesophyl are involved in feeding.

Longitudinal nerve cords transmit information up and down the body.

The evolution of symmetry.

Dugesia, a flatworm from the Platyhelminthes phylum, is mentioned in relation to cephalization.

They are a food source and also produce pearls used in jewelry.

Porifera are characterized by their porous bodies and the presence of specialized cells called choanocytes that help in feeding and water circulation.

Trematoda and Cestoda.

The initial stage involves mitotic cell divisions of the egg, known as cleavages, forming a hollow ball of cells called the blastula.

Noncoelomate invertebrates are the most morphologically simplest animals, including organisms like sponges and jellyfish.

Radial symmetry is when body parts are arranged around a central axis and can be bisected into two equal halves in any 2-D plane, resulting in mirror images of each other.

Aquatic, mostly marine environments.

The male resides in the groove of the female.

Banana slug

Water flow brings food particles in through pores in the epidermis.

Nautilus

The anus (if present) develops either from the blastopore or another region of the embryo.

Snails, slugs, clams, oysters, octopuses, squids.

They reproduce both sexually and asexually.

The evolution of tissues, allowing specialized structures and functions.

They are intestinal parasites with no digestive enzymes.

Examples of organisms in the Clitella class include earthworms (Oligochaeta) and leeches (Hirudinea).

Coelomate invertebrates are animals that possess a true coelom, which is a fluid-filled body cavity completely lined by mesoderm.

Heterotrophy

Eumetazoa exhibit both radial and bilateral symmetry.

The heart pumps blood or hemolymph throughout the body.

Australian beaches

They secrete a mucus cocoon.

The mouth develops later from another region of the embryo.

Porifera are described as aquatic filter feeders.

Sponges

Specialized structures and functions.

Segmentation allows for more efficient locomotion due to the semi-independent movement of individual segments, enabling complex movement.

The discussion progresses from noncoelomate invertebrates to invertebrates with a coelum, and finally to vertebrates.

Phylum Cnidaria includes organisms such as jellyfish, sea anemones, and corals.

Sponges are multicellular.

The coelom is reduced to a small space around organs such as the heart.

Asymmetry means no symmetry, as seen in Parazoa like sponges, which grow as an irregular mass.

The foot serves as a muscular means of locomotion for many molluscs, and is divided into arms or tentacles in cephalopods.

The two types of symmetry in Eumetazoa are radial symmetry and bilateral symmetry.

The clitellum, which resembles a saddle on the worm, is a notable feature of the Clitella class.

Insects have an open circulatory system.

An exoskeleton of chitin or calcium carbonate, or an internal skeleton for muscle attachment.

Most are marine.

Ascaris is an intestinal roundworm whose eggs lie dormant in soil.

Molluscs use gills in filter feeding, where a siphon brings water and food particles to the gills.

They absorb food from the host's gut through their outer surface.

The evolution of a body cavity.

Males are smaller than females and have a hooked end

Proglottids are formed continuously.

They can be found in the feces of the host.

An acoelomate is an animal with no body cavity.

They achieve complex movement by contracting segments of circular and longitudinal muscles.

Cellular organization, Development, Growth, Heredity, Homeostasis, Regulation, Reproduction, Sensitivity.

Annelida have segmented bodies, while Mollusca have a soft body often protected by a shell.

Porifera have a loose body organization with no head, appendages, anus, or mouth, but are multicellular and can change cell types.

Bilateral symmetry is when the body has right and left halves that bisect into two equal halves that are mirror images of each other.

Segmented animals have a series of linear compartments that appear similar but may be specialized in function, such as in earthworms.

1. Nematoda have a complete digestive system with a mouth and an anus, while Platyhelminthes have a gastrovascular cavity with a single opening. 2. Nematoda are generally cylindrical and have a tough outer cuticle, whereas Platyhelminthes are flat and lack a cuticle.

Flukes.

Eumetazoa includes Platyzoa and Bilateria.

In protostomes, the mouth forms first in the embryo, while in deuterostomes, the anus forms first.

Enterobius vermicularis is commonly known as the pinworm.

Flame scallop

No defined tissues, no symmetry, no organs.

Examples of protostomes include flatworms, nematodes, molluscs, and arthropods.

Most are hermaphrodites, having both male and female structures.

Animals are ubiquitous, abundant, and show many variations in structure, behaviors, and lifestyle.

Bilateral symmetry

Cells can disaggregate and reaggregate.

Examples of deuterostomes include echinoderms and vertebrates.

The mantle is a thick epidermal sheet that secretes a shell (if there is one).

They undergo internal fertilization.

They are triploblastic, meaning they have 3 germ layers.

Phylum Platyhelminthes

Most segments are characterized by projections called parapodia, which have chaetae.

Eumetazoa are animals with true tissues that have distinct embryonic layers developing into the adult body.

Two germ layers, making them diploblastic.

The body cavity made possible the development of advanced organ systems.

Cnidaria

Hookworm, which leads to anemia.

A body cavity is a space surrounded by mesoderm tissue that is formed during development, isolated from the exterior of the animal, and is different from the gut or digestive cavity.

By suckers, anchors, or hooks.

Eumetazoa is classified under Para zoa.

The life cycle of Enterobius vermicularis involves eggs being ingested, hatching in the intestines, and adult worms residing in the colon.

Almost all Parazoa are asymmetric, although some have radial symmetry.

They can perform specific functions more efficiently.

Protostomes develop the mouth first from or near the blastopore.

Several specialized cell types including flagellated choanocytes that face the internal cavity, circulate water, and capture & digest food.

The two classes of Annelida are Polychaeta and Clitella.

Coelomates developed a circulatory system to flow nutrients and remove wastes.

Tapeworms and flukes

The radula is a rasping, tongue-like feeding structure found in most molluscs, used for scraping food.

The head is not well developed.

Mantle, Foot, Coelom, Visceral mass, Shell, Radula, Nephridia, Circulatory system.

They range from microscopic to huge.

The mantle is responsible for secreting the shell and can also aid in respiration.

Clitellata are hermaphrodites that cross-fertilize each other.

Nephridia are used to remove nitrogenous waste, serving an excretory function.

No cell walls

A coelom is a true body cavity completely lined by mesoderm, while a pseudocoelom is only partially lined by mesoderm.

It made the development of advanced organ systems possible.

Animals that possess a true coelom, a body cavity fully lined with mesoderm.

The outermost layer of cells in an embryo that develops into the skin and nervous system.

Cnidaria lack reproductive, circulatory, and excretory systems.

Each segment can contain a complete set of adult organs, so damage to one segment is not fatal.

Adults are sessile, meaning they are attached to surfaces such as rocks.

Blood flukes, specifically Schistosoma.

Blue-ringed octopus

Eudoxochiton nobilis

A coelum is a body cavity that lies within tissue derived from the mesoderm.

They can regenerate asexually.

Clades of animals with a coelum are recognized by characteristics such as whether they are segmented or not, if the skeleton is internal or external, and whether they are protostomes or deuterostomes.

Crimson anemone

A clitellum is a thickened band on the body that holds worms together during mating.

These organs are concentrated in the visceral mass.

Jellyfish, corals, and hydras.

Cephalization leads to the development of sensory structures such as eyes and ears.

Dugesia

Bluebottle

Multicellularity

The coelom provides a space for the development and organization of internal organs, allowing for greater complexity and specialization.

Septa (walls) separate the segments.

Some can be pests in gardens or freshwater systems and can carry parasites.

The evolution of segmentation, or repeated body units.

Molluscs typically have an open circulatory system where blood is not always contained within vessels.

Embryonic Development

Nephridia collect waste and transport it out of the body.

The epidermis and nervous system develop from the ectoderm.

Choanocytes circulate water, capture and digest food, and can transform into sperm.

They are an important component of marine food chains.

In an open circulatory system, 'blood' passes from vessels into sinuses, mixes with body fluids, and reenters the vessels.

Marine, freshwater, and moist terrestrial environments

Parapodia are used for swimming, crawling, and burrowing.

No, Clitellata do not have parapodia (feet).

Annelida can be found in many different habitats.

Onchocerca causes river blindness.

A group of animals that lack true tissues and organs, such as sponges.

They are complete hermaphroditic units that contain both male and female reproductive organs.

Young Clitellata develop inside the cocoon.

The coelom acts as a hydrostatic skeleton, aiding in movement and providing support for the body.

Gas exchange occurs by diffusion across body surfaces.

An organism that lacks a body cavity between the digestive tract and the outer body wall.

The innermost layer of cells in an embryo that develops into the digestive tract and associated organs.

The shell provides protection against predators and consists of 2 layers of calcium carbonate.

Trichinosis is caused by Trichinella and is contracted from eating undercooked pork or bear meat.

Stony coral

The osculum is the opening from which water is expelled in sponges.

Pseudocoelomates

Box jellyfish

Earthworms have a closed circulatory system.

Well developed with a mouth and anus, having 2 openings

Mostly marine, some freshwater, and a few terrestrial.

The foot is primarily used for locomotion and can vary greatly in shape and function among different mollusc species.

Wuchereria causes elephantiasis.

Sting humans, resulting in severe pain

Sexual reproduction via internal fertilization

Nephridia are excretory organs that help in the removal of waste products from the body.

The ventral nerve cord is part of the nervous system that coordinates movement.

Tissues

A body plan in which the left and right sides of the body are mirror images.

A fragment of sponge breaks off and grows into a new sponge.

Protostomes develop the mouth first and the anus second, while deuterostomes develop the anus first and the mouth second.

Octopus dolfleini

They can have shells or no shells.

Muscles develop from the mesoderm.

In a closed circulatory system, blood moves continuously through vessels that are separated from body fluids.

They use a scolex that has suckers and/or hooks.

They are carnivores, using stinging tentacles to capture prey.

Longitudinal muscles only, no circular muscles

Hemolymph is the fluid that circulates in the open circulatory systems of some invertebrates, such as insects.

Molluscs have an open circulatory system with a 3 chambered heart.

Each segment has a pair of excretory organs, a ganglion, and a locomotory structure.

Annelida have a closed circulatory system.

Sexual Reproduction

A group of animals in which the anus develops from the blastopore, and the mouth forms later.

An organism that has a body cavity (pseudocoel) that is not completely lined by mesoderm.

The radula is a specialized feeding structure used to scrape food particles.

Acoelomates (no body cavity), Pseudocoelomates (body cavity between mesoderm and endoderm), Coelomates (body cavity entirely within the mesoderm).

Chaetae are chitin bristles that prevent the worm from slipping on the substrate.

Cnidaria have a primitive nervous system that can detect light, touch, and gravity.

The evolution of various patterns of embryonic development.

Animals that have true tissues and are more complex than Parazoa.

Diversity in habitat

A pseudocoelomate has a body cavity located between the mesoderm and endoderm, called the pseudocoelom.

The digestive tract has parts that are specialized for different functions.

It leads to the gastrovascular cavity, which is the site of digestion, most gas exchange, and waste discharge.

Diversity in form

The middle layer of embryonic tissue that develops into muscles, the circulatory system, and other organs.

A coelomate is an animal with a body cavity entirely within the mesoderm, known as the coelom.

A group of animals in which the mouth develops from the blastopore, and the anus forms later.

A body plan in which body parts are arranged around a central axis.

The great diversity of animals seen in the world today.