animal clades

  • Phylum Porifera – Metazoa

  • Sedentary animal (don’t really move)

  • Fresh and marine waters

  • Lack true tissues and organs 

  • Suspension feeders 

  • Phylum Cnidaria - Eumetazoa 

  • Has true tissues 

  • Predators, with specialized cells for purpose

  • Diversified into sessile and motile forms like jellies and corals and hydras 

  • Have relatively simple diploblastic, radial plan (ex. circular) 

  • Body Plan 

  • Sac with central digestive compartment, gastrovascular cavity 

  • Has two variations (sessile polyp and motile medusa) 

  • Has one opening as mouth and anus 

  1. Anthozoa – full time polyps 

  2. Medusozoa – medusa form most of life cycle 


Bilateria Clade

Bilaterian animal have bilateral symmetry and triploblastic development 

  • Lophotrochozoa 

  • Have the widest range of body forms

  1. Phylum Platyhelminthe (flatworms)

  • Live in marine, freshwater and damp terrestrial habitats 

  • Undergo diploblastic development but are acoelomates

  • Flattened dorsoventrally and have gastrovascular cavity (gc)

  • Lack circulatory system but fine branches of gc distribute food

  • Gas exchange across surface, protonephridia regulate osmotic balance 

  1. Phylum Syndermata

  • Rotifers: tiny free living pseudocoelomates – aquatic plankton and has complex digestive system (alimentary canal) compared to flatworms

  • Acanthocephalans: even smaller and parasitic with reduced digestive system   

  1. Phylum Lophophorates

  • Ectoprocts marine and freshwater, are colonial 

  • Brachiopods: marine, are solitary 

  • Feeding structures with tentacles 

  1. Phylum Mollusca

  • Most are marine but some inhabit freshwater and terrestrial 

  • Most have water filled mantle cavity and feed using rasplike radula 

  • Have separate sexes with gonads located in visceral mass 

  • Soft-bodied animals but protected by hard shell 

  • Have closed circulatory system 

  • Body Plan

  1. Muscular foot

  2. Visceral mass

  3. Mantle

  1. Phylum Annelids

  • Have bodies composed of a series of fused rings 

  • Cephalization (has something similar to a brain) 

  • Bilateral symmetry, complete gut and concentration of sensory system in head 

  • Coelomates and Protostome 

  • Longitudinal and circular muscles, hydrostatic muscles that helps them move 

  • Close circulatory system (lets long distance transport) 

  • Ecdysozoa

Most species rich animal group – sister taxa to lophotrochozoa 

→ tough and have hard outer coat (cuticle) 

→ growth via ecdysis, shedding outer shell (molting) 

  1. Phylum Nematodes (roundworms) 

  • Thick but soft, cuticle is shed then regrows

  • Have an alimentary canal, but lack circulatory system 

  • Pseudocoelom transports nutrients throughout body 

  • Longitudinal body wall muscles 

  • Mass sexual reproduction 


  1. Phylum Arthropoda 

  • Segmented with tagmosis (when multiple parts of the body are fused)

  • Diverse appendages, can be used to do multiple things – all joint (to reproduce, feed, walk, etc)

  • Covered by exoskeleton of protein and chitin 

  • Has open circulatory system – has hemolymph (not blood)

  • Variety of organs specialized for gas exchange 

  • Has 4 subphyla 

  1. Cheliceriformes/Chelicerata

  • Claw-like feeding appendages 

  • Most are extinct – ex. Horseshoe crab and scorpions

  • Arachnids (spiders), included, have 4 pairs of appendages so multiple legs 

  • Gas exchanges occur in respiratory organs (book lungs)

  • Produce silk from abdominal glands

→ can be used for prey catch or defense 

  1. Myriapods

  • Terrestrial 

  • Tagmosis between head and trunk only

  • Jawline mandibles

  • Class Diplopoda – has two pairs of legs per segment

  • Class Chilopoda – one pair of legs per segment 

  1. Hexapoda (insects)

  • Most species of any living group

  • Tagmosis between head, thorax, and abdomen 

  • Two pairs of wings and can fly

  • Has three pairs of legs 

  • Tracheal system for gas exchange (series of tubes where every cell is attached has access to outside for gas)

  • Growth and Metamorphosis

→ incomplete: young go through multiple stages of molts until they reach full size (ex. roaches) 

→ complete: larval stages like caterpillars (ex. moths) 

  1. Crustacea

  • Tagmosis in Cephalothorax and Abdomen 

  • Are biramous – two branches and can be modified

  • Two pair of antennae 

  • Dominant marine arthropod and animal

  • Has three important groups

→ Isopod: terrestrial, freshwater, marine species 

→ Decapods: relatively large (ex. Lobsters, shrimp)

→ Copepods: planktonic and has many species, most numerous of all animals (krills) 

  •  Deuterostomia 

  1. Echinodermata 

  • Ex. sea stars, are slow moving or sessile marine animals 

  • Thin epidermis covers endoskeleton 

  • Simple nerve net with central coordination 

  • Sexual reproduction is external 

  • Radially symmetrical in adults while juveniles are bilaterally symmetrical (RADICAL CLEAVAGE) 

  • Deuterostome, anus from from blastopore 

  • Echinoderms have unique water vascular system

→ has network of hydraulic canals branching into tube feet that function in multiple things

  1. Chordata

  • Defined by set of derived characters  

  • Some are only expressed during embryonic development

  • Notochord: longitude flexible rod that provides skeletal support, not mineralized of large fluid cells and fibrous tissue 

  • Dorsal Hollow Nerve cord: develops plate of ectoderm cells that rolls into hollow neural tube, develops into central nervous system 

  • Muscular, post-anal tail: tail posterior to anus, in vertebrates generally only present in embryonic development 

  • Pharyngeal Clefts: grooves on pharynx in chordate embryos, will develop slits with function in suspension feeding and gas exchange 

→ Tetrapods development to ears and jaws 


Surface Area and Volume

  • Increase amount of SA of organ can allow for greater acquisition of necessary substances (tissues that interact with the outside to get more stuff like food and water) 

  • Large volume relative to SA can lead to the loss of contents (like heat, food) more compared to small volume relative to SA

→ Volume determines functional capacity 

  • Cephalochordata 

  1. Lancelets 

  • Feeble swimmers  but swim with muscles similar to those of fish

  • Feeds on plankton and buried in sand mainly 

  • Urochordata

  1. Tunicates

  • Sea squirts, have a larval and adult form 

  • Sister group to vertebrates 

  • Larval form showing morphological trait shows relation 

Vertebrata Clade

  • Vertebrates are chordate with a backbone

  • Has more complex nervous system

  • Has two clusters of HOX genes

  • Neural crest, collection of cells near dorsal margins of closing neural tube in embryo 

→ gives rise to variety of structures including some bones and cartilage of skull 

  • Myxini

  • Hagfish, slime used for production and can be produced liters at a time

  • Petromyzontida

  • Oldest living lineage of vertebrates

  • Jawless vertebrates inhabit marine and freshwater 

  • Cartilaginous segments surround notochord and arching partly over nerve cord 

→ ex, lampreys are jawless 

→ Gnathostomes Clade

  • Evolution of jaws

  • Vertebrates that have jaws, may have evolved from slits from skeleton support 

  • Adaptive value of jaws

→ more efficient respiration 

→ can hold teeth and anti predator defense

→ allowed diversity in diet and feeding modes (herbivory and carnivory)

  • Chondrichthyes

  • Sharks, rays and ratfish (~1000 species) 

  • Mostly marine 

  • Entirely cartilaginous skeleton 

  • Actinopterygii 

  • Ray finned fishes 

  • > 27000 species and includes >95% of fish

  • ~50% of vertebrate diversity 

  • Marine and freshwater

→ Evolution of lungs, allows breathing air 

  • Actinistia & Dipnoi 

  • Lobe-finned fish

  • Have rod shaped bones and surrounded by layer of muscle in pelvic and pectoral fins

  1. Actinistia

→ marine 

→ thought to be extinct 

→ 2 species of coelacanths

  1. Dipnoi 

→ evolved in ocean but now all freshwater

→ breathe using underwater with gills and surface by gulping air into lungs 

→ 6 species of lungfish (sister group to tetrapods) 


→ Walking on Land 

  • Tetrapods, took use of lungs and limbs for them to move onto land 

  • Lobe-fins evolved into limb and feets 


  • Tetrapods

  1. Amphibians (frogs, salamanders, etc.) 

  • Strong dependent on water

  • Moist and unprotected skin

  • Eggs without shells 

  • Frogs have survived all of the 5 planet wide mass extinction events up to now 

  1. Amniotes (reptiles and mammals) 

  • Evolution of amniotic egg (containing membrane that protects embryo) allowing departure from wet environment 

  • Extra-embryonic membranes 

  • Amnion: membrane that encloses embryo

  • Chorion: protects embryo and organs

  • Yolk sac: encapsulates and protects yolk 

  • Allantois: respiration and receives waste 

  • Water impermeable skin 

  • Ribcages help ventilate lungs for respiration

→ allows study structural for organs, provides more surface area for gas exchange 

  • Differentiated by skill structure  

  • Anapsid: no hole behind eye socket 

  • Diapsids: 2 holes behind eye sockets, strong jaw muscles 

  • Synapsids: 1 hole behind eye socket


  1. Reptiles (lizards, birds, extinct dinosaurs, etc.) 

  • Scales that provide waterproof barrier and lay shelled eggs 

  • Most are ectothermic, gaining heat for metabolic processes from external 

  • Birds are endothermic, generate heat internally for processes and activity 

  1. Feathered theropods evolved into birds, archaeopteryx is the oldest bird 

  2. Evolved from dinosaurs 

  3. Derived changes allowed for feathers, lighter skeleton for flight

  4. Birds have air sacs instead of lungs, since its lighter and more efficient  (parabronchi) 

  1. Mammals

  • Mammary glands that produce milk 

  • Has hair and a bigger brain 

  • Differentiated teeth 

  1. Monotremes

  • Small group of egg laying mammals (ex. platypus) 

  1. Marsupials

  • Embryo develops within  placenta in moms uterus 

  • Born very early in development 

  • Embryonic development while nursing (ex. kangaroo) 

  1. Eutherians 

  • Have longer period of pregnancy, completes embryonic development within uterus and joined to mom by placenta

  • (ex. Humans, elephants, whales)