What traits do you think the following organisms all

share in common?

Use the defining characteristics of fish that you just learned to help guide you.

Sea star

Sea urchin

Sea cucumber

Sand dollar

Brittle star

Invertebrates:• Kingdom: Animalia• Phylum: ????????????????

We are now going to look at several other phyla as we move through the end of the course that are still grouped in the animal kingdom, but lack a spinal chord (invertebrates).

-Kingdom: Animalia-Phylum: Echinodermata

Echinoderms – Stars of the Sea

Echino = spinyDerm = skin

Echinoderms – Stars of the Sea-At first glance, it may be impossible to group the various forms of echinoderms together.

-Examples: Sea stars, sea urchins, crinoids, brittle stars, sand dollars, sea cucumbers.

-They can all look extremely different, but with a closer look they actually possess many similarities.

Echinoderms – Stars of the Sea-The major characteristic that all echinoderms have in common: 1) Body has no segments (this is a common distinguishing characteristic for any invertebrate)

Echinoderms – Stars of the Sea-The major characteristic that all echinoderms have in common: 2) Radial symmetry – divided into 5 parts

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5

•Every arm has an equal share of the animal’s systems!

3) Water vascular system – water suction system for moving around/self-defense (almost like hydraulics)

Echinoderms – Stars of the Sea

pedicellariatube feet

*Most have tube feet

Echinoderms – Stars of the Sea4) Ossicles (a.k.a. test) – a solid “skeleton-like” structure that makes echinoderms rigid.

*They are made of calcium carbonate (like sea shells) and have different shapes for each class of echinoderm.

Provides stability and protection.

Echinoderms – Stars of the Sea5) Dermal Branchia – Respiration/gas exchange. These are small soft lumps on the exterior of the body that absorb oxygen for respiration.

Oxygen from water

•Every arm has an equal share of the animal’s systems!!!!

•They can regenerate arms!!!

Echinoderms – Stars of the SeaReproduction – can be asexual or sexual.*asexual = regeneration of limbs

*Sexual = free spawning

-Sea stars actually have an “eye” at the end of each arm called an ocellus.

-It allows them to recognize light and dark areas, not actually see figures.-Their other main senses are taste (with mouth parts/chemical receptors) and feel (with nerves near tube feet)

Echinoderms – Stars of the Sea

-So closely related to chordates (us) because their development stages are very similar to ours!

1)We are both dueterostomes (first embryonic opening, or blastopore, becomes anus). 2)In all other sea organisms, it becomes the mouth (protostomes)3)We both have bilateral symmetry during developmental stages.

-Thus, sea cucumbers are our closest relative in the sea (other than the vertebrates)

Us and echinoderms

All other marine invertebrates

-Echinoderms are often times used as an “indicator species” in marine environments.

-They play an important role in shallow water ecosystems, so their presence or absence usually tells scientists how healthy the ecosystem is.

A healthy balance of these 2 pictures

represents a healthy ecosystem.

An overgrowth of kelp means the water is not healthy enough to support urchins. (urchins eat the kelp)

An area with no kelp means the water is healthy, but something is wrong with the otter/sea star population. (otters/stars eat urchins)

Army of sea stars

Eyespot (ocellus)

SKETCH 1 – Label the arms, ocelli, and madreporite. Also, describe function of the madreporite.

Tube feet

SKETCH 2 – Draw the ventral side of the starfish, including the labels above.

SKETCH 3 – Open the starfish on the dorsal side. Label the circled parts of the internal anatomy.

SKETCH 4 – Draw a picture of JUST the water vascular system. Label all circled parts of the anatomy. Explain the function of the water vascular system below the sketch.

Analysis

• List 5 characteristics of the starfish that you expect to see tomorrow during the sea urchin dissection.

Sea UrchinMove using extended tube feet

Eat using mouth parts called “Aristotle’s Lantern”

Gonads are a delicacy in some cultures.

Spines can cause painful, infected stings (few are venomous)

SKETCH 1 – EXTERNAL VENTRAL SIDE (you will see the mouth, spines, and pedicellaria)

SKETCH 2 – EXTERNAL DORSAL SIDE (you will see the anus and madreporite)

SKETCH 3 – carefully cut an opening on the side of the urchin. (be careful cutting around the sharp spines). Once you open the urchin, first draw the digestive and reproductive organs.

-Stomach/Intestines (brown on the diagram)-Reproductive glands (pink on the diagram)

SKETCH 4 – Now draw the water vascular system (blue on the diagram). Water travels in through the madreporite, travels down through the stone canal into the ring canal, and finally gets moved through each of the 5 radial canals where water is pumped into and out of tube feet to move the urchin along the sea floor.

SKETCH 5 – Aristotle’s LanternWith the urchin open, remove the solid tooth-like organ directly above the mouth. This is actually 5 separate teeth surrounded by muscle that the urchin uses to chew. This organ is known as Aristotle’s Lantern. Draw the mass.

List 5 characteristics of sea urchins that you

expect to see on Tuesday in the sea cucumbers.

Sea Cucumber-Sea cucumbers are essentially elongated urchins without the spines.

-The are widely dispersed and have been found in every area of the ocean floor.

-They can extrude gonads and other internal organs through their anus as a self defense mechanism. (allow predator to eat these organs or sometimes they are sticky and trap the predator to avoid being eaten).

Radial Symmetry

Over 2,500 species have been discovered with a huge variety of colors, sizes and appendages.

Madreporite

The tentacles are just modified tube feet to help snatch small prey.

Sketch 1 – External anatomy. Sea cucumbers are just elongated sea urchins without the spines. You will see tube feet for transport just like the urchin. They have a continuous digestive system with a mouth inside a group of tentacles and an anus at the other end.

Find the madreporite, where water is pulled into the water vascular system.

The gonad will take up more space than the picture displays. Label the gonads and then remove them to reveal the other internal organs.

Sketch 2 – reproductiveThese are the organs that the cucumbers can push out to distract or trap potential predators.

Label the pharynx (throat), stomach, intestines, and anus

Sketch 4Water vascular system

Behind the reproductive and digestive organs you will find the water vascular system. As with the other echinoderms, label the madreporite, stone canal, ring canal, radial canals, and tube feet.

There was no mention of any ossicle (skeleton) in this echinoderm dissection. They do have an ossicle, how do you think it might be incoroporated into their body structure?

It is made of thousands of tiny individual microscopic parts.