Biology final Invertebrate Evolution and Diversity

How did animals originate?

they evolved from single - celled eukaryotes similar to present - day choanoflagellate protists

Basal animals are sessile but what are most animals?

mobile

What are the requirements for fossil records?

Hard outer feature , Common and Has to be buried

What was soft bodied, mostly sessile animals living 575 - 542 mya, forming the earliest seafloor communities of large multicellular life including porifera and cnidarians

Ediacaran biota the first fossils

What includes bizarre rangemorphis w/ fern like fractal bodies that lived in deep water and likely absorbed nutrients directly from seawater ?

Ediacaran biota the first fossils

What are early diverging animal groups?

Porifera and cnidaria

What does Porifera include?

sponges that retain sessile traits observed in the Edicaran biota

What does Cnidarians include?

include ancient and modern corals, sea anemones and sea jellies

What is a sponge body like?

a sac perforated with pores

Since a sponge is a filter feeder what does it capture?

it captures particles suspended in the water that passes through it body

Chaoancyte = ?

absorbs

Explain how water is drawn and flows.

water is drawn into a central cavity the spongocoel and flows out through the osculum

What uses tentacles to capture prey, tentacles contain cnidocytes?

Carnivores

What is the purpose of ecological engineers?

reef- building corals and other colonial cnidarians create three dimensional habitats that structure entire marine ecosystems

How did the body become more complex

because of the tissue, which ultimately influences the environment in different ways

What created tissue development?

Embryonic change

What includes cnidarians that are diploblastic with radial symmetry and a simple nerve net, that marks a major step up in complexity from sponges?

Eumetazoans

What evolved a gastrovascular cavity with a single opening that functions as both mouth and anus?

Cnidarian body plan

What happens during gastrulation?

Endoderm

The endoderm does not get pushed all the way through?

diploblastic

What does not have a digestive system but it has a gastrovascular cavity?

diploblastic

What is a predators that use tentacles to capture and consume prey?

Cnidarians

What is armed with cnidocytes, unique cells used in defense and prey capture?

Tentacles

Specialized organelles within cnidocytes that eject a stinging thread

Nematocysts

What are the two variations on the body plan?

the sessile polyp and motile medusa

What adheres to the substrate by the aboral end of the body (the end opposite the mouth) ?

Polyps

What is a free swimming form that has a bell - shaped body with the mouth on the underside ?

A medusa

What does life cycle alternates between?

polyp and medusa body forms

What can reproduce both asexually (through budding) or sexually (through production of medusae) ?

Medusozoans life cycle

What does Medusa allow?

sexual reproduction

When did the diversity of large animals increased dramatically & marks the earliest fossil appearance of many major groups of animals ?

during the Cambrian Explosion

What does higher O2 allow?

animals to support larger more active bodies with energy hungry muscles and nerves

What allowed for complex tissues and skeletons form and be maintained and oxygen pulses in late ediacaran - cambrian line up with burst of animal diversification ?

rise of atmospheric oxygen

What did the expansion of hox toolkit give?

give precise control over body patterning along the head tail axis

What can small changes in Hox regulation generate?

many new body plans quickly

Changes in Hox genes rapidly make?

rapid opportunity for diversity of body plants at this time

What triggered an evolution arms race?

Appearance of active predators

What created new ecological niches and lifestyles accelerating animal diversification ?

new predaotr - prey relationships

Explain animals in early Cambrian oceans?

they were diverse in morphology, way of life and taxonomic affiliation

What are the three clades that Bilaterians have diversified into ?

lophotochozoa, ecodyszoa, deuterostomia

What has three different approaches to making a complex body plant that has difference pros and cons associated with them?

Diverse animal groups radiation in aquatic environments

What is the first animal group to be bilaterian and have triploblastic development?

Lophotochozoans

What was identified by molecular data, but is named for its morphology ?

Lophotochozoans

Mesoderm = ?

more complex tissue can develop

What has a external cuticle, secreted by the epidermis?

Ecdysozoans

What need to be done to grow the cuticle in Ecdysozoans?

must shed, or be molded and replaced with a larger one

When did molting evolve?

500 mya apparently only once. All ecdysozans have a single common ancestor

When is the cuticle sheded?

during ecdysis or molting

What is the largest of eight ecdysozoan phyla ?

Arthropods

What is the estimated amount of arthropods on earth?

a billon

What is two of every three known species of animals called and what are found in nearly all habitats on earth?

Arthoropods

What's considered the most successful animal group because they are in every environment ?

Arthoropods

Explain the body plan of arthopods.

consist of a segmented body, hard exoskeleton and joined appendages

How many years ago does the arthropods date back? (Early arthropods, such as trilobites, showed little variation from segment to segment)

to the cambrian explosion 535 - 525 million years ago

What united to form body regions specialised for feeding, walking or swimming ?

Overtime segments

What happed during Arthropod Evolution ?

Diverse body plans like arose due to changes in the sequence or regulation of existing Hox genes rather than the acquisition of new ones

Who were the first animals to colonize land following the Cambrian explosion?

Arthopods

What follows plants in colonization of land?

Arthropod Terrestrialization

What has eyes olfactory receptors and antennae that function in both touch and smell ?

Arthopods

Explain what the open circulatory system.

it uses a heart to pump hemolymph into the cavity surrounding the tissues and organs (the hemocoel)

Pods = ?

legs

What are the three major lineages that living arthropods consist of diverging from early in phylum's evolution?

Chelicerates (sea spiders, horseshoe crabs, ticks, mites and spiders

Myriapods ( centipedes and millipedes

pancrustaceans ( insects, lobsters, shrimp, barnacles)

Why are arthropods successful on land?

they are protective, waterproof exoskeleton, highly effective movement and has flexible life histories and diets