Invertebrates ReviewFertilized egg 2 cell stage 4 cell stage 8 cell stage Morula Blastula GastrulaBlastula hollow ball of cellsBlastocoel forms in the process of gastrulation where the blastula begins to move inward.Blastopore hollow tube openingArchenteron the hollow opening due to gastrulation.

Diploblastic jellyfish and hydra have ectoderm and endoderm. Mouth and anus from same hole.Triploblastic Other animals have a mesoderm that lies between ecto and endo.Protostomes mouth forms first from the blastoporeDeuterostome anus forms first from the blastopore

Annelids (Worms)

Coelom - body cavities lined by a mesoderm-derived tissue that also suspends the organs contained within. Hydrostatic Skeleton.

Phylum Cnidaria (Hydra)

Polyp form is sessile (tentacles up) and the Medusa form is free swimming.

Cnidocytes specialized cells that immobilize their prey or for protection. They contain nematocysts, capsules that discharge stinging barbed projectiles.

Gastrodermis has gland cells that secrete digestive enzymes into the body cavity coelenteron and nutritive cells, which absorb nutrients from the cavity via endocytitic vacuoles.Epithelomuscular cells contractile fibers run perpendicular to them that allow the animal to constrict the vascular cavity (decrease in diameter).Interstitial cells stem cells that can give rise to different cell types.

Locomotion Inch their ways along substrates by amoeboid movement of cells of the basal disc. Vascular cavity acts as a hydrostatic skeleton and hydras extend their bodies by contracting muscle fibers or retract their bodies by contracting longitudinal fibers.

Diet and Acquisition Prey comes near and tips cilium nematocyst fires tentacles engulf prey Digestion. They receive help from unicellular algae = symbiotic relationship

Excretion Form ammonia and it diffuses from the cell layers and is carried away by water currents. Defecation feces come out the mouth/anus (indigestible remains of the animal).

Circulation/Respiration Lack both systems. Simple diffusion of dissolved oxygen and CO2 between the dermal layers and the environment. Natural water currents help.

Nervous System Decentralized Nerve Net nerves interlaced in mesoglea and extend to sensory cells, epitheliomuscular cells.

Reproduction Asexual reproduction with good conditions by budding. Poor conditions make hydras form gonads hermaphroditic.

Earthworm (Lumbricus terrestris)

Phylum Annelida first true coelomic cavity with related organs grouped into definite regions (body systems) and they have the metamerism body segmentation of serially repeating parts.

Septa side walls that are composed of connective tissue that is sandwiched between two layers of epitheliomuscular cells mesotheliumClitellum thickened ring of glandular epithelium divides the worms anterior and posterior regions.Metamere body segments.Prostomium hangs over the mouth but is not considered the first segment of the worm.Peristomium the first segment that surrounds the mouth

Epidermis columnar epithelium that contains sensory and secretory cells. The secretory cells retard desiccation of the worm.Circular and Longitudinal Muscle decrease diameter and increase length and the other one increases diameter and decreases length.Peritoneum covers the longitudinal muscles at the tips. It lines the body wall and surrounds the coelom space cavity between the inner body wall and the gut.

Earthworms Complete digestive tract. Bilateral symmetry. Hydrostatic Skeleton. Closed circulatory system. No specialized system for gas exchange (Respiratory) diffusion of dissolved gases across epidermis

Typhlosole increases surface area to help absorb more nutrients.Nephridium Excretion

Locomotion Longitudinal and Circular Muscles. If setae of the segments posterior to the contraction are anchored to the soil, it results in pushing the anterior segments forward.

Diet and Acquisition Crop food storage Gizzard muscular walls mechanically grind up the contents into small particles increasing SA hydrolyzed by enzymes released in the Intestine. Columnar Epithelium dissolved nutrients from intestine absorbed and then transferred to the chloragogen tissue Chloragogue cells process nutrients, convert Carbs into Glycogen (like Liver in animals), proteins deaminated and the nitrogenous waste (ammonia) is converter to urea. They can also synthesize hemoglobin. Anus undigested material (castings) are eliminated here

Excretion Nephridia coelomic fluid is pulled into the Nephridium by the beating action of hair-like cilia. The capillaries return valuable reabsorbed nutrients to the blood stream. Nephridiopore urine is excreted through here.

Circulatory Dorsal Blood Vessel blood travels anteriorly to the pseudo-hearts Pseudo-hearts contractile vessels, which connect the dorsal and ventral blood vessels. They serve as accessory pumps. Ventral Blood Vessel blood travels posteriorly, branches off into lateral branches to enter organs but then comes back using the lateral branches of the dorsal blood vessel.

Respiration Diffusion of CO2 and O2 across the moistened epithilium. No true system for gas exchange.

Nervous System Cephalization a concentration of sensory and neural structures toward the head of organism. Suprapharyngeal (cerebral) and subpharyngeal ganglion are the two masses of neurons that are connected by two nerve bundles called the circumpharyngeal connectives. Ventral Nerve Cord extends from subpharyngeal ganglion all the way to the last body segment.

Reproduction Hermaphrodite = monoecious = contain a complete set of functional male and female structures. Seminal vesicles lateral extensions of reservoirs and serve as sites of maturation of sperm. Seminal receptacles where male sperm is fertilized and where the cocoon forms.

Crayfish (Cambarus)

Bilateral SymmetryOpen Circulatory System

Locomotion Walking legs can move the crayfish forward, backward or sideways. Abdominal Flexor Muscles flew or curl the tail downward and toward the anterior, which causes the uropods to act as fins and propel the fish backward. Abdominal Extensor Muscles stretched the flexor muscle so it can contract again.

Diet and Acquisition Chelipeds can be used to capture food or for self defense 3 Pairs of Maxillipeds handle and reduce the size of food particles as they are passed to the mandibles. Mandibular Adductor Muscles move the mandible to crush the food through contractions. Mouth Esophagus Cardiac Stomach Cardiac Stomach - contains ossicles with teeth gastric mill with the help of anterior and posterior gastric muscles grind, mix and regrind food in the stomach. Digestive Glands secrete enzymes, which catabolize the absorbed nutrients, producing ammonia. The n-waster diffuses out of gland to the surround hemocoel.

Excretion Mostly excrete n-waste through gills, which is done by diffusion across epithelium surfaces. Green Glands small amount of secretion mainly osmoregulation.

Circulation - brachiopericardial canals Open circulatory system. 5 arteries that leave the anterior portion of the heart Ophthalmic artery blood to brain and eye stalks Antennal Arteries blood to organs like stomach, green glands, and antenna. Hepatic arteries supply the digestive glands Dorsal Abdominal Artery supplies blood to tissues including gonads and abdominal muscles. Sternal Artery supply blood to ventral nerve and other tissues. As blood travels through the gills, blood gases are exchanged with the surrounding water. Blood from the gills is drawn into the brachiopericardial canals pericardial sinus blood back to the heart via the gills.

Respiration - Gills

Nervous System Supraesophageal Ganglion brain. Circumesophageal Connectives pass posteriorly on either side of the esophagus to join the subesophegeal ganglion that lies deep within the exoskeleton. Ventral Nerve Cord travels all the way to down to the last abdominal segment.

Reproduction Male releases his sperm through the gonopores and inserts its into the females seminal receptacles. The sticky fertilized eggs bind to female swimmerets/pleopods.