Topic 19 Flashcards
How to define an Animal
Multicellular, heterotrophic eukaryotes with tissues that originate from embryonic laters
Characteristics of Animals
- Cell structure and specialization: multicellular and lack cell walls.
- Animal somatic (non-reproductive) cells differentiate into specialized types
- Nutritional mode (chemoheterotrophs)
- Reproduce sexually or asexually (fission, budding, parthenogensis
- Development
Pathenogenesis
A form of Animal asexual reproduction that is the development of an embryo from an unfertilized egg cell
Direct Development
Animal development where the animal after birth/emergence from an egg is a smaller version of its adult form
Indirect development
A form of animal development that intervening stages (larvae) with morphological and behavioural differences from the sexually mature adult stage.
Ex) caterpillar»_space; butterfly
Define Body Plan
A set of morphological and developmental trains that include symmetry, body cavities, and tissues
Radial Symmetry
Animal body plans where the animal’s body has symmetry on every access
Animals w/ this body plan are often sessile or planktonic
Bilateral Symmetry
Animal body symmetry with a distinct left and right side and a single plane of symmetry along a head-tail axis
Cephalization
The development of a head region containing sensory organs and common for bilateral symmetry
Define Tissue
Specialized groups of cells with common structures and/or functions, which are isolated from other tissues by membranous layers
Tissue Development
During development, distinct embryonic cell layers (germ layers) give rise to tissues/organs through Ectoderm and Endoderm
Ectoderm
The germ layer covering the embryo’s surface and gives rise to the skin and nervous system
Endoderm
The innermost germ layer of an embryo that lines the developing digestive tube, the archenteron
Biploblastic animals
Animals with two embryonic cell layers (ectoderm and endoderm) that are typically radially symmetrical
Triploblastic animals
Animals with ectoderm, endoderm, AND MESODERm that give rise to muscles and other organs.
Common for bilaterally symmetrical animals
Have a fluid-filled body cavity
Coelom
A fluid-filled body cavity that is developed during embryonic development of the mesoderm in larger animals that allow internal organs to shift without deforming and cushions the organs
Functions as a hydrostatic skeleton
Hemocoel
A body cavity in many tiploblastic animals that forms between the mesoderm and endoderm from the blastocoel
Hemolymph
The fluid inside hemocoels that is analogous to blood and circulates through the body cavity in an open circulation system by the heart
Involved in internal circulation, nutrient transport, and waste removal
Two Categories of Bilateral triploblastic animals
Protostome development
Deuterostome development
Differ in embryo cleavage, coelom formation, and fate of the blastopore
Protostome Development Traits
Cleavage is spiral and determinate where each new cell is predetermined to form a specific part of the later embryo
The coelom forms through splitting of solid masses of mesoderm
The blastopore becomes the mouth
Deuterstome development Traits
Cleavage is radial and indeterminate allowing each each cell in early stages of cleave to be able to develop into a complete embryo
Mesoderm folds from the wall of the archenteron to form the coelom
The blastopore becomes the anus
Key Features of Animal Phylogeny
- Share a single ancestor of a colonial flagellated protist
- Sponges are basal animals
- True animals is a clade of animals with true tissues
- Most animal in Clade Bilateria with bilateral symmetry
- Three major clades of bilaterian are all invertebrates except most of Chordata
Eumetazoa
“True animals” is a clade of animals with true tissues
Three Major Clades of Bilaterian animals
- Deuterostomia (hemichordates, echindoerms, and chordates)
- Ecdysozoans (shed their exoskeletons)
- Lophotrochozoans (tentacle covered feeding structure like molluscs)
