Body Organization
Sponges do not have the organization seen in most animals, which explains why they were initially confused with plants. When compared to the symmetrical organization of many other organisms, sponges seem to have no organization at all. Sponges do not have symmetry, as that is developed in later-evolving organisms. Although sponges do have some specialization to facilitate nutrient gathering and reproduction, they do not have true organs or true tissues.
Sponges do not have the organization seen in most animals, which explains why they were initially confused with plants. When compared to the symmetrical organization of many other organisms, sponges seem to have no organization at all. Sponges do not have symmetry, as that is developed in later-evolving organisms. Although sponges do have some specialization to facilitate nutrient gathering and reproduction, they do not have true organs or true tissues.
Everyday Functions
Sponges do not need to thermoregulate. Grown sponges are sessile, which means they are attached to a certain location, and do not move. To obtain nutrients, sponges rely on the flow of water. Pores on the surface of the body give way to canals, created by the spicules. These canals are lined with specialized cells, although they are not well organized. One type of cell has a flagellum, which is moves rapidly to keep the water flowing within the cell. Meanwhile, other cells remove nutrients from the water as it passes through the canals. After nutrients are removed, the water leaves the sponge through vents. |
Reproduction
Sponges are capable of reproducing both sexually and asexually, and most sponges are hermaphroditic, or capable of producing both types of gamete. Asexual reproduction among sponges occurs through budding, and complete regeneration is possible with a very small sample from the original cell. However, it is far more common for sponges to reproduce sexually. Each sponge produces only one type of gamete per spawn. Those who produce sperm release it into the water, where it uses water flow to find an egg producer. Following internal fertilization, larvae are released. They float around for a few days, before coming to rest at a spot, and beginning to grow, becoming sessile. |