Bio 2 Exam #3 - Kingdom Animalia (Supergroup Opisthokonta)

Common Characteristics of Animals

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* All animals have ***multicellularity*** — Proteins help transition organisms from single celled to multicellular
* One protein = **GK_PID**
* ***Heterotrophs*** = have to take in energy sources (carbon) from outside of themselves to make building blocks = ingest their food as *consumers* and nutrients are absorbed — diverse modes
* No cell walls (no cellulose or chitin) → ***flexibility***
* Allow for faster movement
* Drawbacks = cells need other means of support inside cytoskeletons and outside (exoskeleton) (different support network involving filaments, etc)
* Extracellular matrix between cells = important structural proteins (collagen)
* ***Nervous tissue***: rapid response
* Ability to create action potential → go out to gland cells to muscle cells, controls muscle tissue
* ***Muscle tissue***: movement
* All animals have smooth muscles (a lot also have skeletal muscles = body movements/large movements); also have cardial muscles (pump blood throughout cardiovascular system)
* ***Sexual reproduction***
* Small, mobile sperm delivered to larger egg (**diploid zygote**) → ball of cells = **blastula** → Acquires GI tract and become **gastrula**
* Extracellular matrix between cells: 27 different types of **collagen** (important structural protein in animals)


* Special clusters of ***Hox genes*** → patterns body axis
* **Similar rRNA**
* Cells communicate with each other via gap junctions → Characteristic cell junctions: anchoring, tight, gap

Metamorphosis

dramatic change in body form across an animal’s life history under the control of genetic information

Hox genes

Developmental genes that regulate other genes; important in embryonic development = controlling transition from blastula to gastrula to other stages; arms, legs, back, front

Gap junctions

Allow passage of signals from one cell to the next immediately

Anchoring junctions

Hold cells together = allow movement in unison

Tight Junctions

Create barriers → Regulate passage of material from one side of the cells to the other = make materials flow through cells

* EX.: (tightest junction) blood brain barrier = designed to keep substances/toxins from getting direct access to the brain

GK_PID

Protein that orients the meiotic spindle apparatus to help keep the cells from dividing in their correct planes

* following their genetic program + related to DNA synthesis genes and enzymes

Embryonic Stages of Animals (Cleavage)

Zygote → Eight cell stage → Blastula (hollow ball of cells → Blastocoel (Cross section of blastula) → Gastrulation → Gastrula (Has blastocoel, endoderm, ectoderm, blastopore)

History of Animal Life

Multicellular animals emerged at the end of the Proterozoic eon (over 600 mya)

* First animals were **invertebrates** 


* A sudden increase in animal diversity occurred during the **Cambrian explosion** 
* 3 explanations:
* favorable environment (warm temps, increase in atmospheric + aquatic oxygen, development of ozone layer = protection)
* evolution of *Hox* gene complex
* an evolutionary “arms race” — adaptive radiation = Shells were an important part 

Vertebrate Evolution

* Fishes = 1st group of vertebrates to arise (greatest amount of diversity + species)
* Plants colonized land around same time fishes were diversifying = provide a food source for animals on land 
* Life on land presents important challenges = complete reorganization of body form as animals move from water to land → dramatic changes in animal bodies to adapt 
* Animals developed lungs, internal fertilization (gametes dry out quickly in air), amniotic egg (laying eggs in pond/ocean) 
* Reptiles dominated the Earth for millions of years (successful) — Mesozoic Era helped with diversification, but KT Explosion caused dinosaurs to die out, giving way to an explosion in the number and diversity of mammals

Invertebrates

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* Without a backbone 
* 97-99% of all animals (a lot of diversity)
* Heterogeneous assemblage of groups (>35 phyla) 
* *No single positive character shared in common by all invertebrates* 
* EX.: sponges, jellyfish, “worms,” crustaceans, insects, clams, snails, sea stars

Vertebrates

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* With a backbone (have a vertebral column) 


* 1% of all animals 
* 1 phylum = **Chordata** (biggest subgroup of Chordata) 
* EX.: fish, frogs, birds, reptiles, mammals, humans

Strategy for classifying animals

GOAL = ***Integrate structure and function in evolutionary context*** 


1. Bauplan
2. Establish evolutionary relationships


1. Framework to organize and compare bauplans
2. Who is related to who + how they work together
3. Functional principles


1. Physical, chemical, biological, physiology, developmental, ecology
2. Body design is determined by: type of environment they live in, size of animal (SA:V ratio), mode of existence (how they make a living — parasitic or free-living?),  constraints of genome (ancestral design — zebras only produce zebras, plants only produce plants) 

Bauplan

* Basic design (ground plan) of each major taxonomic group = forms our starting point (no new bauplan since Cambrian Explosion)


* All our current phyla = represented in the Cambrian Explosion 

Metazoa

Another name for “animals

* Means “multicellular animal life” 


* Debate about whether or not Metazoa are true animals (missing some characteristics) 
* Ground plan for all animals = cells → specialized tissues → **Epithelia** & **Connective Tissue** 
* Body size:
* Prokaryote → Protozoans → Animals 

Epithelia

outside covering/lining (like of organs or pathways), joined cells through membrane junctions on basal lamina, (sometimes modified with) cilia, supported by connective tissue 

Connective Tissue  

forms bulk of animal body 

* cells often separated from each other in extracellular matrix (contains cells + fluid called ground substance) + fibers (collagen) organized into a skeleton (endo- or exo-)

Cellular Level of Animals

Include **Porifera (Sponges)**

* Put in groups (Parazoa) → Does not contain all animal characteristics but enough to be characterized as such
* Aggregations of cells, groups with specialized functions (reproduction, support, drawing water through sponge body = Division of labor) 

Cell-tissue Level of Animals

Includes **Cnidaria and Ctenophora**

* Groups of similar cells arranged in definite patterns or layers with a common function = Tissue 


* **Diploblastic** = 2 layers of tissue (epithelia + gastrodermis) 
* Don’t really have muscle cells 
* Many scattered cells still present 

Tissue-organ Level of Animals

Includes **Platyhelminthes (Flatworms)**

* Tissues arranged into organs 
* Organ consists of multiple tissue types and has a very specialized function 
* Not very defined systems 
* Epithelial tissue 
* Connective Tissue 
* Muscular tissue 
* Nervous tissue

Organ-system level of Animals

Includes everyone else (**Lophotrochozoa, Gnathifera, Ecdysozoa, Chordates, etc.)**

* Groups of organs working together to perform a particular function


* Systems associated with basic body functions
* 11 body systems: (maintain homeostasis) **integumentary, muscular, skeletal, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, immune, reproductive**

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Integumentary System

Skin — protection, respiration (gas exchange), nutrient uptake (absorption), coloration, temperature regulation

Muscular System

* All about movement — not just physically but also moving food through digestive system
* Accomplished through different types of muscles like **skeletal muscle** (bigger movements like swimming), **cardiac muscl**e (designed to propel blood through circulatory system), **smooth muscle** (popular among animals — especially in invertebrates = forms bulk of internal organs like in stomach or lungs; designed for internal movements)

Skeletal System

Support, operate with leverage (muscles pull on bones to operate as levers and offer full support), storage (materials stored in fluid or in bones)

Nervous System

* All about control -- Reception/flow of information, analysis, coordination of response
* All nervous systems operate on the same flow of information— start with receptor or structure designed for receiving info → groups of neurons that analyze signal → coordination of response (like movement or secretion)
* Very efficient (immediate response)

Endocrine System

* regulation of growth, metabolism, and sexual development/function → mediators = chemicals traveling in bloodstream from widely separated organs (diffuse tissues throughout bodies)
* slower, long-term processes

Circulatory System

* Series of capillaries that link arteries and veins (**arteries** = carry blood AWAY from the heart vs. **veins** = carry blood back to the heart) → heart serves as pump
* All cells have to be in close proximity to the circulatory system
* Designed for delivery of O2, nutrients, hormones; removal of CO, ammonia, and metabolic wastes (to not cause problems)
* Cardiovascular System= circulatory + lymphatic system

Lymphatic System

* Most under-appreciated system scattered throughout the body → important for transport, protection, fat absorption
* Fluid travels through this system and is picked up by the tissues and returned to circulatory system to maintain constant blood volume
* Also key for protection because it is tied to immune system → encounters lymph nodes = first interaction between cells and foreign objects (filters the lymphs)
* Fats are easier to get into lymphatic system before entering circulatory system

Respiratory System

All about gas exchange → getting oxygen in, getting CO2 out

Digestive System

* Collection of food (swallowing, ingestion = mechanical breakdown)
* chemical breakdown of nutrients
* absorption of nutrients (when they cross lining of GI tract)
* egestion of waste

Urinary System

* Water balance → maintaining water in body
* Nitrogenous waste elimination → come from breakdown of proteins (amino group with nitrogen) — nitrogen can be toxic (like in ammonia)
* Produce urea or ammonia or uric acid (semi-solid waste product from animals like birds)

Immune System

* Only vertebrates have specific defenses = specialized group of cells that mount your response to something foreign in a very specific way and remember them after they have seen it
* vs. non-specific = work against anything that is foreign

Reproductive system

Procreation \= perpetuating the species

Radiata (Radial Symmetrical Animals)

any plane that passes through the central axis (defined by oral (where mouth is) and aboral axis) divides the animal’s body into sides that are mirror to each other = 2 mirrored right and left sides (longitudinal axis)

* With the **sac body plan,** there is only one opening into the gut (more primitive)
* Sensory structures concentrated on the outside edges (no head) = diffused nervous system

sac body plan

* there is only one opening into the gut (more primitive)
* One opening = serve as both the mouth + anus so animal can’t eat continuously
* Influences how large they become + can’t engage with too much vigorous movement b/c food will come right back out

Bilateria (Bilaterial symmetrical animals)

definite right and left halves on the outside 

* Divide into different planes: (describe where body parts are relative to each other)  
* **Frontal plane = dorsal/ventral**
* **Sagittal plane = right/left**
* **Transverse = anterior/posterior** 
* Strongly associated with a definite head end in animals → **cephalization** = concentration of sensory structures + feeding structures in the head end of the animal that allows the animal to sense and respond to the environment head first — forward movement 
* **“tube within a tube” =** long linear system → open at one end and at the opposite end/formation of 2 openings to the gut

“tube within a tube” body plan

* long linear system → open at one end and at the opposite end/formation of 2 openings to the gut
* leads to specialized areas for different activities = more efficient  (especially for digestion = can eat continuously) 

Diploid life cycle

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* Diploid life cycle → 2 copies of every chromosome in every cell in body 
* Specialization through gene expression → turned on 
* Sperm and egg (haploid) = produced by meiosis 
* Sperm + egg fuse at fertilization which results in a zygote 
* the one-celled stage of an individual of the next generation
* Undergoes mitosis 
* Then results in multicellular embryo that gradually takes on features determined when zygote was formed 
* All growth occurs as mitotic division
* As a result of mitosis, each somatic cell in body:
* Has same number of chromosomes as zygote
* Has genetic makeup determined when zygote was formed

Cleavage

describe early cell divisions → basically mitosis without any growth within the cells = important to form the blastula → determine what it becomes  

Germ layers

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* Group of cells that behave as units during early embryonic development 
* Give rise to tissue/organ/system = **Morphogenesis** 

Diploblastic

* 2 germ layers: **Ectoderm** (outer layer)& **Endoderm/Gastroderm** (lines gastrovascular cavity, so it secretes digestive enzymes and connects animal cells to the nutrient sources) 
* Non-cellular layer in between 2 germ layers = **Mesoglea** → there are fibers present and is jelly-like; cells wander through it

Triploblastic

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* 3 embryonic germ layers: **Ectoderm** (forms skin/epithelial layer, outer covering, integumentary system + nervous system, hair, nails, sensory — ears, eyes),  **Mesoderm** (Makes up bulk of animal’s body, associate with muscle + skeletal system + circulatory system)**, Endoderm** (digestive = inside, forming primitive organs like stomach, liver) 
* Becomes tissues, organs, and systems in animal’s body

Coelom (Body Cavity)

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* fluid-filled space (hydrostatic skeleton — form a means of support + structure) around the gut in which organs are suspended 
* Offers more space, more SA, storage, support, increases body size/complexity

Acoelomate

Triploblastic animals with no body cavity 

* Find endoderm, ectoderm — in between = mesoderm with a solid mass of cells but no space

Blastocoelomate/Pseudocoelomate

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* “false body cavity” b/c it is lined by one side only by mesoderm 
* Blastocoelom (AKA pseudocoelom) = Fluid-filled space derived from blastula/blastocoel

Eucoelomate

* Humans are this (bulk of animal cavity) 
* True body cavity = Fluid-filled space lined on all sides by mesodermal tissue 
* **mesentery** = bands of tissue = hang organ from body wall

Segmentation

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* Repeated body units = **segmentation**/**metamerism** 
* Body may be divided into regions along longitudinal axis called **segments** (repeated organs, bands) 
* Advantages = If some organs get damaged, others can take over 
* Occurs in annelid worms (, arthropods (fused body segments = **tagmata**), and chordates (In muscular system or vertebral column)  
* Allows specialization of body regions
* More efficient locomotion 
* Might not be in every region but key

Protosome

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* 1st embryonic opening becomes the mouth (most of Bilateria: Annelids, Arthropods, Molluscs)
* Cells divide at 45 degree angles into the spaces between cells (some cells at the top = small and at bottom = large) → cleavage pattern known as **spiral cleavage** **→** hollow ball of cells 
* **Determinate cleavage** = fate of cells are specified very early on (8-cell stage) — each of those cells are destined to become a particular structure in animal’s body (genetic programming = turned on) 
* The embryo at this point is called a **Mosaic embryo**
* If pluck out one cell at 16-cell stage = defective embryo → unable to form certain parts 
* **Schizocoely** = Mesodermal bands splits in the middle as it enlarges to form the coelom 
* Blastopore becomes mouth, archenteron = primitive gut 

Deuterostome

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* 2nd embryonic opening becomes the mouth (Echinoderms, Chordates) 
* Cells are more or less the same size = dividing at vertical + horizontal orientation (90 degree angles) = **Radial cleavage** → more organized = develop tiers of cells 
* **Indeterminate cleavage →** results in **regulative embryo**
* genetic programming in the cells is not yet set (up to 32 cell stage) — all of the cells are the same/identical = still not differentiated 
* If pluck out a cell at 16-cell stage = other cells will make up for it + plucked cell will give rise to a complete functional embryo (identical offspring) 
* **Enterocoely** = Specialized cells in endoderm start to differentiate and grow larger and ultimately give rise to a coelom → Archenteron outpockets to form coelom 
* Blastopore becomes anus

Stem Cells

**Pluripotent** :

* Retain ability to develop into *any cell type* 
* Retain capacity to divide 
* Adult stem cells = multi- (become other couple type of cells) or uni- potent (one other type of cell) 

Phylogenetic Tree of Animals

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* Choanaflagellates → share common ancestor with fungi + animals (ancestral) 
* Basal (closest to the origin) to the rest of the animal kingdom = clade **Ctenophora** = exhibit *rotational s*ymmetry (180 flip of body parts rather than mirror image) but don’t have hox genes 
* Side group = **Parazoa** (Porifera) = don’t have Hox genes or specialized tissues but have specialized cells (parallel to the animals) 
* **Placozoa = flat multicellular animals that are marine, no real symmetry, but have** ***ghost Hox*** **genes** 
* True multicellular animals = Cnidaria, Ctenophora, Bilateria (**eumetazoa**)
* Have specialized cells + tissues 
* Radial + bilateral symmetry 

Murder Hornets

AKA *Vespa Mandarinia*

* Has mandaratoxin which is lethal with several stings or if allergic → kill 30-50 people/year or a few can kill 30k honeybees in a few hours 
* 1 can kill 40 bees/minute through decapitation → feed thorax to their offspring 


* Japanese honeybees have developed methods against the murder hornets → let the hornet into their nest and, together, the honeybees swarm it and vibrate at one, causing the temperature to rise → slowly roasts the murder hornet alive