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Zoology Lec Finals Coverage, Lecture notes of Zoology

De La Salle Araneta University (DLSAU)Zoology

Organ Systems (2) Taxonomy Phylums

Typology: Lecture notes

2019/2020

Available from 10/15/2024

anezhka-lim 🇵🇭

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ZOO LEC FINALS

Organ Systems (2)

Digestive System

- 3 general types of animal diet

- Herbivores (plants)

- Carnivores (meat)

- Omnivores (both plants and meat)

Generalized functions of organs

Mouth - food entrance

Salivary glands - some digestion of starch

Esophagus - carries food to stomach

Stomach - protein digestion

Pancreas — liver

Small intestine - digestion and absorption

Large intestine - salts and much water absorbed

Anus - excretes waste

Ingestion

●There are four ways on how animals can ingest

their food

○Suspension feeding happens when the

animal captures food particles that are

suspended in the water (e.g. corals).

○Substrate feeding is when an animal

lives on their food source (e.g.

caterpillar).

○Fluid feeding happens when animals get

nutrients from the fluid of another

organism (e.g. mosquito).

○When an animal eats pieces of other

organisms, it is considered bulk feeding.

Digestion – the breakdown of large food into smaller,

soluble food molecules

Absorption – mechanism that obtains nutrients from the

food that we eat

Elimination – removal of undigested food and other

debris

Digestion occurs in specialized compartments

●Most animals have an alimentary canal with

○Mouth

○Anus

○Specialized regions

Invertebrate digestive system showing

(a) a cnidarian with single opening that moves

materials to and from the gastrovascular cavity

and

(b) a nematode having an alimentary canal with

separate entry of food and exit of waste.

The length of the digestive tract often correlates with

diet

Partial preview of the text

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Organ Systems (2) Digestive System

3 general types of animal diet
- Herbivores (plants)
- Carnivores (meat)
- Omnivores (both plants and meat) Generalized functions of organs Mouth - food entrance Salivary glands - some digestion of starch Esophagus - carries food to stomach Stomach - protein digestion Pancreas — liver Small intestine - digestion and absorption Large intestine - salts and much water absorbed Anus - excretes waste Ingestion ● There are four ways on how animals can ingest their food ○ Suspension feeding happens when the animal captures food particles that are suspended in the water (e.g. corals). ○ Substrate feeding is when an animal lives on their food source (e.g. caterpillar). ○ Fluid feeding happens when animals get nutrients from the fluid of another organism (e.g. mosquito). ○ When an animal eats pieces of other organisms, it is considered bulk feeding. Digestion – the breakdown of large food into smaller, soluble food molecules Absorption – mechanism that obtains nutrients from the food that we eat Elimination – removal of undigested food and other debris Digestion occurs in specialized compartments ● Most animals have an alimentary canal with ○ Mouth ○ Anus ○ Specialized regions Invertebrate digestive system showing (a) a cnidarian with single opening that moves materials to and from the gastrovascular cavity and (b) a nematode having an alimentary canal with separate entry of food and exit of waste. The length of the digestive tract often correlates with diet

● Herbivores and omnivores have relatively longer digestive tracts than carnivores Avian digestive system has crop for food storage. The stomach has two chambers: the proventriculus producing the gastric juices, and the gizzard where the food is stored and mechanically digested. Most of the chemical digestion and absorption happen in the intestine while the cloaca excretes waste. Monogastric digestive system has one chambered stomach. The process begins in the mouth where ingestion and mechanical digestion takes place. Chemical digestion may also start in the mouth through the help of the saliva. Peristalsis (the alternate contraction and relaxation of muscles) moves the bolus through the esophagus to the stomach. Gastric juices in the stomach aids in digestion. Nutrients are absorbed in the small intestine while reabsorption of water takes place in the large intestine. Feces are excreted through the anus. Ruminants have four chambered stomachs to aid in the digestion of plant materials. The four compartments are called the rumen, reticulum, omasum, and abomasum. These chambers allow digestion of plant materials with the help of microorganisms. The abomasum is considered the true stomach that functions like a monogastric stomach where gastric juices are secreted. Osmoregulation and Excretion

Osmoregulation maintains the constant osmotic pressure in the fluids of an organism via the regulation of water and salt concentration. This mechanism is an important part of homeostasis to maintain normal body functions in animals. Animals balance the gain and loss of water and solutes through osmoregulation Osmoconformers ● Have The Same Internal Solute Concentration seawater ● Many Marine Invertebrates Are Osmoconformers Osmoregulators ● control their solute concentrations ● Freshwater fishes Salt water fish
Loses water by osmosis
Drink seawater
Pump out excess salt The urinary system plays several major roles in homeostasis The excretory system ● Expels wastes ● Regulates water balance ● Regulates ion balance For land animals, water is gained by drinking and eating, and lost through evaporation and waste disposal. To maintain salt-water balance, water is conserved through waterproof skin and through the specialized function of the kidneys that concentrate urine thereby eliminating excess nitrogenous waste (urea). Filtration ● Blood pressure forces water and many small solutes into the nephron Reabsorption ● Valuable solutes are reclaimed from the filtrate Secretion ● Excess H+ and toxins are added to the filtrate Excretion ● The final product, urine, is excreted Immune System
a complex network of cells, proteins and other molecules that defends the body against infection. INNATE IMMUNITY ● Set of inborn, fixed general defenses against infection ADAPTIVE IMMUNITY ● Set of immune defenses tailored to specific pathogens encountered by an organism during its lifetime The lymphatic system becomes a crucial battleground during infection The lymphatic system is a network of ● Lymphatic vessels

Located outside the CNS
Consists of:
- Nerves (bundles of fibers of sensory and motor neurons) and
- Ganglia (clusters of cell bodies of the neurons) The peripheral nervous system of vertebrates is a functional hierarchy ● Somatic nervous system
Carries signals to and from skeletal muscles
Mainly in response to external stimuli ● Autonomic nervous system
Regulates the internal environment
Controls
Smooth muscle
Cardiac muscle
Organs of various body systems Parasympathetic
restores the body to a state of calm Sympathetic
activates the fight or flight response during a threat or perceived danger Diversity of animal nervous systems.
cnidarians have nerve cells forming nerve net
echinoderms have nerve cells bundled into nerve fibers
planarians have central ganglia acting as the brain in processing information
arthropods have peripheral ganglia along the ventral nerve cord
octopus have complex brain with millions of neurons
vertebrates like humans have central and peripheral nervous systems Endocrine System The endocrine system consists of glands (ductless) that produce hormones regulating the metabolism, growth and development, tissue function, sexual function, and reproduction, among others. Hormones are chemical signals secreted by the endocrine glands neurosecretory cells that are usually carried in the blood to cause specific changes in target cells. Hormone signaling involves three key events: (1) reception of hormone via a receptor protein, (2) signal transduction, (3) response within target cells.

Reproductive System Asexual reproduction results in the generation of genetically identical offspring Asexual reproduction ● One parent produces genetically identical offspring ● Very rapid reproduction ● Can proceed via ○ Budding ○ Fission ○ Fragmentation/regeneration Sexual reproduction results in the generation of genetically unique offspring Sexual reproduction ● involves the fusion of gametes from two parents ○ Resulting in genetic variation among offspring ○ Increased reproductive success in changing environments Sperm may be transferred to the female by ● External fertilization

Many fish and amphibian species
Eggs and sperm are discharged near each other ● Internal fertilization
Some fish and amphibian species
Nearly all terrestrial animals
Sperm is deposited in or near the female reproductive tract *Frogs in an embrace that triggers the release of eggs and sperm *Anemone fish protecting its spawn as it utilizes external fertilization Phylogeny and Systematics ● Evolutionary biology is about both process and history. ● The processes of evolution are natural selection and other mechanisms that change the genetic composition of populations and can lead to the evolution of new species. ● Phylogeny is the evolutionary history of a species or group of related species REVIEW OF EVOLUTION (Note these important points) ● Individuals do not evolve: populations evolve ● Natural selection can amplify or diminish only heritable traits; acquired characteristics cannot be passed on to offspring ● Evolution is not goal directed and does not lead to perfection; favorable traits vary as environments change A mass of other evidence reinforces the evolutionary view of life ● Biogeography, the geographic distribution of species, suggested to Darwin that organisms evolve from common ancestors ○ Darwin noted that animals on islands resemble species on nearby mainland more closely than they resemble animals on similar islands close to other continents ● Comparative anatomy is the comparison of body structures in different species ● Homology is the similarity in characteristics that result from common ancestry ○ Vertebrate forelimbs Sorting Homology from Analogy

Phylum Porifera (sponges) General Characteristics ● The simplest multicellular invertebrates ● The oldest metazoan (animals made up of more than one type of cell) group still extant on our planet ● Body is an assemblage of cells embedded in a gelatinous matrix and supported by needle-like spicules and protein (no tissue-level organization) ● Exclusively aquatic animals fixed on the substrate and live by drawing in water and filtering microscopic size food particles from it [Sessile (adult) or motile (larva) animals] ● Depend on water currents to bring them food and oxygen and to carry away their body waste Form and Function ● Pores as body openings ● Numerous ostia for incoming water ● One to a few large oscula(s.osculum) as water outlet ● Central cavity called spongocoel Canal Systems Different Shapes of Skeleton Digestion ● Sponges lack complex digestive, respiratory, circulatory, reproductive, and nervous systems. ● All other major body functions in the sponge (gas exchange, circulation, excretion) are performed by diffusion between the cells that line the openings within the sponge and the water that is passing through those openings. Reproduction and Development

Many are capable of asexual and sexual reproduction
Most sponges are monoecious/hermaphroditic (male female sex organs in one individual)
Oocyte retained; sperm ejected Gemmules
atypical type of asexual reproduction is found only in freshwater sponges and occurs through formation of gemmules
Tiny organisms develop into sponges

Important for survival (embryo is hidden in the capsule for protecting when environment is unfavorable) Ecological Relationships ● Most of the 5000 or more sponge species are marine and about 150 species live in freshwater ● Embryos are free-swimming but adults are always attached usually to rocks, shells, corals or other objects ● Many animals such as crabs and fish live as commensals or parasites in or on sponges Classifications Class Calcarea
Exclusively marine
Predominantly inhabit shallow tropical waters
Often have vase-like forms
Spicules with calcium carbonate
Spicules needle - shaped, three- or four rayed
Canal Systems either asconoid, syconoid, or leuconoid. Class Hexactinellida
Glass sponges
All marine, mostly deep water
Usually dull in color
Spicules six-rayed siliceous
Body often cylindrical or funnel-shaped
Canal systems: syconoid or leuconoid Class Demospongiae
Largest and most diverse class
Huge variety in form and color
Siliceous spicules present and/or skeleton of spongin fibers or fibrillar collagen
Canal system leuconoid
One family freshwater, the rest are marine
Order Poecilosclerida
Carnivorous sponges
Prey on variety of small invertebrates via phagocytosis of fragments Class Homoscleromorpha
Marine sponges commonly found in shallow habitats and in dark or semi-dark ecosystems.
Flagellated pinacocytes
With viviparous (producing living young) cinco blastula (wrinkled, flagellated larva)
Skeleton tetraxonicsilicious Phylum Cnidaria
most primitive eumetazoan (true tissue organization)
Primary radial symmetry
With two germ layers: ectoderm, endoderm
With gastrovascular cavity
Some with true skeleton, some hydrostatic
Two membrane layers: epidermis and gastrodermis with mesoglea (jelly-like connective layer) in between
With differentiated cell types in each tissue layer (primitive)
Two basic types of individuals: polyps and medusae
Some are polymorphic (2 body plans during life cycle)
Exoskeleton or endoskeleton of chitinous, calcareous or protein components in some
stinging cells (cnidocytes) containing stingers (nematocyst)
To be able to catch their prey Feeding and Digestion
prey on various organisms
Mouth opens into gastrovascular cavity which communicates with cavities in the tentacles
Digestion starts in the gastrovascular cavity (extracellular digestion) but nutritive muscular cells phagocytize many food particles for intracellular digestion
Amoeboid cells may carry undigested particles to the gastrovascular cavity, where they are eventually expelled with other indigestible matter Respiration, Excretion, and Circulation
Generally “absent”
Diffusion between cells Nervous System
Primitive
Nerve cells scattered across the body (functions like sensory and motor neuron) Reproduction

Some structural adaptations for parasitism: penetration glands, organs for adhesion such as suckers and hooks Life Cycle of Clonorchis sinensis
host can be more than 1
From feces lalabas yung egg
Egg go to intermediate host
Becomes free living larvae
To fish and encyst
Human eat, encyst in duodenum
Intermediate host (human)
Definitive host (mollusk)
Parasitic adaptation
Hookers and suckers to attach to host Class Monogenea
mostly external parasites that clamp onto the gills and external surfaces of fish using a hooked attachment organ (opisthaptor) Class Cestoda
tapeworms
Usually have long flat bodies composed of a scolex, for attachment to the host, followed by many reproductive units (proglottids)
Main body is a chain of proglottids called strobila
Nearly all monoecious
Usually requires two hosts
Normally, adult tapeworms do little harm to their host Life Cycle of Dipylidium caninum
Gravid proglottids which contains the eggs is being released from the feces
Eventually, eggs will be released out to the environment
Eggs can then be acquired by the host
Host can infect another host Phylum Annelida ● Freshwater, marine, terrestrial, parasitic ● Metameric (segmented), bilateral symmetry ● Hydrostatic skeleton (except in leeches) ● Acellular external cuticle ● Sometimes called “bristle worms” because, except for leeches, most annelids bear tiny chitinous setae that helps anchor segments during locomotion to prevent backward slipping or for aquatic forms, it is used for swimming ● Modification of the nervous system such as the presence of cerebral ganglia (brain) ● Closed circulatory system with muscular blood vessels and aortic arches (“hearts”) for propelling blood ● Respiratory gas exchange through skin, gills or parapodia ● Excretion via metanephridia (primitive “kidney”) ● Reproduction: hermaphrodite or separate sexes, asexual in some (budding) Body Plan ● Typically with two-part head (Prostomium and peristomium), series of segments (metameres) and a terminal pygidium bearing an anus ● Contraction of longitudinal muscles causes the segment to shorten and become larger in diameter while contraction of the circular muscles causes it to lengthen and to become thinner ● Crawling motion via peristaltic contraction ● Distinct clitellum (reproductive structures) in Oligochaetes and leeches, reproductive structure present about 1/3 of the way down the body ● Clitellum generates mucus that aids in sperm transfer and gives rise to a cocoon within which fertilization occurs ● Some are monoecious (earthworm and leeches) or dioecious (polychaetes). Cross fertilization (reciprocal insemination) is preferred in hermaphroditic animals. Ecological Relationship
Parasitic and commensal symbioses with other species in their habitat Classifications Class Polychaeta
All are marine
Segments show well developed lateral outgrowths, called parapodia, with many setae.
A distinct head is present with eyes, tentacles, cirri and palps. Class Oligochaeta
Freshwater and terrestrial worms are included
Head is not distinct
Setae are in each segment
Clitellum is present
All are bisexual animals
Complete digestive system Subclass Hirudinea
Freshwater, marine, or terrestrial worms
Parasitic or predators
Setae are absent
Suckers usually present
Bisexual animals and fertilization is internal Nematoda General Characteristics
Triploblastic

Bilaterally symmetrical
With chitinous external “skeleton”
Not segmented
Have a complete digestive system
Have separate sexes
Presence of sensory organs (with exceptions)
Mostly are intestinal parasites
Rings do not reflect true internal body segmentation
Have longitudinal muscles only which accounts for whip-like motion of their movement
Excretory system not well developed (diffusion)
Nervous system via four longitudinal nerve cords which fuse at the anterior end forming the “brain” (head ganglia)
Reproduction: monoecious, dioecious, or parthenogenetic Habitat

Intestinal a. small intestines: Ascaris, hookworms, Strongyloides, Capillaria b. large intestines: Trichuris, Enterobius
Extraintestinal a. Lymph nodes/vessels: Wuchereria and Brugia b. Eyes and meninges: Angiostrongylus c. Muscles: Trichinella Infective stages and Modes of Transmission
Ingestion of embryonated eggs – Ascaris, Trichuris, Enterobius
Ingestion of infective larva – Capillaria, Trichinella, Angiostrongylus
Skin penetration of L3 – hookworms and Strongyloides
Vector-borne – Wuchereria and Brugia
Autoinfection – Strongyloides and Enterobius
Transmission through inhalation – Enterobius and Ascaris DEVELOPMENTAL STAGES
Egg
Larva a. L1 : rhabditiform larva b. L2: c. L3 : filariform larva
Adult Ecological Relationship

Some free-living, some parasitic
Found in different habitats Ascaris lumbricoides Common name: Giant intestinal/roundworm Final Host : man Habitat : small intestine Diagnostic stage : fertilized and unfertilized egg Infective stage : embryonated egg Source of ex. to inf. : soil-transmitted helminth MOT : Ingestion Pathology: Ascariasis Diagnosis: Stool Exam, Concentration technique Drug of choice: Albendazole (Mebendazole and Pyrantel Pamoate) Ascaris suum – Ascaris of Pigs Morphology Life cycle of Ascaris lumbricoides
adult cya sa sa humans and nagmamature and mag lay ng eggs
Can travel from intestine to lungs and other parts of body get infected Classifications Class Chromadorea
pore-like or slit-like amphid apertures vary from labial
pores or slits to post-labial elaborate coils and spirals
cuticle usually annulated (ring-like), sometimes ornamented with projections and setae
phasmids present or absent, generally posterior
esophagus is usually divided into bulbs, with 3 to esophageal glands
excretory system glandular or tubular
female with one or two ovaries
caudal alae present or absent Class Enoplea
amphids pocket like, not spiral, usually post-labial
cuticle smooth or finely striated
phasmids present or absent
esophagus cylindrical or bottle-shaped with 3 to 5 esophageal glands, stichosome or trophosome present in some simple non-tubular excretory system, usually a single cell
female generally with two ovaries
male generally with two testes
caudal alae rare Amphid - invagination of the cuticle; olfaction (sense of smell) Phasmid - smaller than amphid; in the tail end Alae - unclear function, to strengthen the cuticle Phylum Mollusca ● One of the largest animal phyla after Arthropoda ● Predominantly in marine environments ● Key characteristics:
Muscular foot
Visceral mass containing internal organs

First pair of appendages modified to form chelicerae (for feeding/inject venom)
Pair of pedipalps and four pairs of legs
No antennae, no mandibles
Prosoma (cephalothorax) and opisthosoma (abdomen) - Class Merostomata - Aquatic chelicerates - Cephalothorax + abdomen - Compound lateral eyes - Appendages with gills - Class Pycnogonida - Body chiefly cephalothorax - Usually with four pairs of long walking legs - One pair of subsidiary legs for egg bearing - Mouth on long proboscis - Class Arachnida - Two body regions - 4 pairs of legs and 2 pairs of mouth part appendages (chelicerae and pedipalps) - Order Scorpiones - scorpions - OrderAranaea - spiders - Order Opiliones - harvestmen - Order Acari - ticks and mites Subphylum Crustacea
Mostly aquatic with gills
Cephalothorax usually with dorsal carapace
Head appendages consisting of two pairs of antennae
One pair of mandibles and two pairs of maxillae
Sexes usually separate
Class Branchiopoda
Flattened, leaf like swimming appendages with respiratory function
Class Maxillopoda
Five cephalic, six thoracic and usually 4 abdominal segments
No typical appendages on abdomen
Unique maxillopodan eye
Class Malacostraca
Shrimps, crayfishes, crabs, lobsters
Usually with 8 thoracic and 6 abdominal segments each with a pair of appendages Subphylum Myriapoda
Appendages numerous
Head appendages consisting of one pair of antennae
One pair of mandibles and one or two pairs of maxillae
Typically found in moist soils, decaying biological material, and leaf litter.
Class Diplopoda
Millipedes
Subcylindrical body
Head with short antennae and simple eyes
Body with variable number of segments
Short legs, usually two pairs of legs to a segment
Separate sexes
Class Chilopoda
Centipedes
Dorsoventrally flattened body
Variable number of segments, each with one pair of legs
Legs in the first segment are modified to form poison claws
One pair of long antennae
Separate sexes Subphylum Hexapoda
Body with distinct head, thorax, and abdomen
Pair of antennae
Mouthparts modified for different food habits
Head of six fused segments
Thorax of three segments
Usually sic somites
Separate sexes
Class Entognatha
Base of mouthparts lies within the head
Mandibles have one articulation
Class Insecta
Bases of mouthparts exposed and exiting head capsule
Mandibles generally have two regions of articulation Phylum Echinodermata ● Endoskeleton of plates or ossicles ● Water - vascular system ● Radial or biradial symmetry ● No head or brain but with radial nerves ● Endoskeleton of dermal calcareous ossicles ● Locomotion by tube feet which project from the ambulacral groove ● Digestive system usually complete ● Excretory organs absent ● Sexes separate Class Asteroidea (sea stars)
Familiar along shorelines and may also live on muddy and sandy bottoms and among coral reefs
Pentaradial symmetry Class Ophiuroidea (brittle stars)
Largest group in terms of number of species
Posses five arms that are slender and sharply set off from their central disc
Five movable plates surround the mouth serving as jaws, no anus Class Echinoidea (sea urchins)
Compact body enclosed in an endoskeletal test
Lack arms Class Holothuroidea (sea cucumbers)
Greatly elongated compared to other Echinoderms
Cephalization is absent

Tube feet are typically used for movement in species that crawl over the surface of the sea bottom
Hydrostatic skeleton Class Crinoidea (sea lilies)
Relatively primitive characteristics
Attached to a substrate
Five flexible arms branch to form many more arms Reproduction
Sexually dimorphic
Release their eggs and sperm cells into water
Fertilization is external
May also reproduct asexually, as well as regenerate body parts lost in trauma Ecological Importance
sea cucumbers burrow into the sand, providing more oxygen at greater depths of the sea floor
source of food and medicine (some sea cucumber toxins slow down the growth rate of tumor cells)
Sea urchins are also model organisms used in developmental biology research
hard skeleton of echinoderms is used as a source of lime which is added to the soil to allow plants to take up more nutrients Phylum Hemichordata
Marine animals formerly considered a subphylum chordates based on their possession of gill slits, a rudimentary notochord, and a dorsal nerve cord (their notochord is not homologous with that of chordates)
Wormlike bottom dwellers. Phylum Chordata Five Chordate Hallmarks ● Notochord - a skeletal rod, present at some stage in the life cycle ● Single, dorsal, tubular nerve cord - anterior end of cord usually enlarged to form a brain ● Pharyngeal pouches - present at some stage in the life cycle; in aquatic chordates these develop into pharyngeal slits ● Postanal tail - projecting beyond the anus some stage but may or may not persist ● Endostyle - in the floor of pharynx or a thyroid gland derived from the endostyle Urochordata (tunicate)
With tunic, a cellulose-like carbohydrate which covers the outer body
Only the larval form possesses all four common structures
Adults only maintain pharyngeal slits and lack a notochord, a dorsal hollow nerve cord, and a post-anal tail Cephalochordata (lancelets)
Possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail in the adult stage Subphylum Vertebrata ● Integument Basically Epidermis And Dermis ● Distinctive cartilage or bode endoskeleton consisting of vertebral column and a head skeleton ● Complex muscle segments to provide movement ● Complete, muscularized digestive tract ● Closed circulatory system with a ventral heart of multiple chambers ● Well-developed coelom divided into pericardial and pleural peritoneal cavities ● Excretory system via kidneys ● Highly differentiated tripartite brain ● Endocrine system of ductless glands Jawless fishes
Class Myxini and Class Cephalaspidomorphi
Slender, eel-like body with naked skin
Fibrous and cartilaginous skeleton
Jaws absent
Dorsal nerve cord with distinct brain
Digestive system without distinct stomach Class Myxini
Hagfishes
Marine group the feeds on dead or dying fishes, annelids, mollusk and crustaceans (are scavengers and predators)
5 to 16 pairs of gills Class Cephalaspidomorphi
Lampreys
Commonly grasp a stone to hold its position in a current
Parasitic lamprey attach themselvesby their suckerlike mouth to fish and with their sharo keratinized teeth rasp through flesh and suck body fluids Class Chondrichthyes
Body fusiform (except rays) with a heterocercal caudal fin
Mouth ventral
Skin with placoid scales
Endoskeleton entirely cartilaginous
No swim bladder or lung
Separate sexes; oviparous (eggs), ovoviviparous (eggs hatch after release) or viviparous (live young); direct development; internal fertilization Class Osteichthyes
Skeleton with bone of endodermal origin
scales usually cycloid and ctenoid
Paired and median fins supported by dermal fin rays
Jaws present
Respiration primarily by gills
Swim bladder often present

Zoology Lec Finals Coverage, Lecture notes of Zoology

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